Publish Year: 2019 Title: Color-Change Spessartine Garnet: A First Report Abstract: Figure 1. Color-change phenomenon was observed in this 2.11 ct octagonal mixed-cut spessartine. The left image, with a dark green color, was taken using an LED light source with 6500K color temperature (a daylight-equivalent light simulator). The right image, showing a dark red color, was taken with an LED light source with 2700K color temperature (an incandescent light simulator). Photos by Robison McMurtry and Diego Sanchez.

GIA’s Carlsbad laboratory recently examined a 2.11 ct faceted stone (figure 1) that showed strong color change from dark green under daylight-equivalent lighting to dark red under incandescent illumination. Standard gemological testing revealed a refractive index that was over the 1.80 RI limit of the GIA desktop refractometer. This was the first example of a color-change garnet with an over-the-limit RI reading examined by GIA. Fluorescence was inert to long-wave and short-wave UV light. The stone did not show any pleochroism with the dichroscope. Using a handheld spectroscope, we observed a cutoff at about 460 nm and a broad band centered at about 575 nm. Microscopic examination revealed only a small fracture and strong internal strain. High-order interference colors were observed in cross-polarized light from the strain along grain boundaries.
Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) results showed that the stone was composed predominantly of spessartine (80.37 mol.%), with minor contributions from other end members of the garnet species (see supplementary table 1). It is classified as a spessartine garnet based on the criteria in the pyrope-spessartine-almandine ternary diagram (figure 2, left) modified from Stockton and Manson (“A proposed new classification for gem-quality garnets,” Winter 1985 G&G, pp. 205–218). The RI and SG could also be calculated based on chemical composition (W.A. Deer et al., Rock-Forming Minerals: Orthosilicates, Vol. 1A, Geological Society of London, 1982, pp. 485–488). The calculated RI and SG—plotted in figure 2, right—were 1.797 and 4.182, respectively. The calculated RI value was consistent with the measured RI value. In 2001, Krzemnicki et al. reported a garnet composed of 76.9 mol.% spessartine and 4.2 mol.% goldmanite with a color change from orange-yellow under daylight-equivalent lighting to reddish orange under incandescent illumination based on the colorimetric data in the article, although color change from brownish green to brownish was observed visually (“Colour-change garnets from Madagascar: Comparison of colorimetric with chemical data,” Journal of Gemmology, 2001, Vol. 27, No. 7, pp. 395–408). The high spessartine and goldmanite composition of the stone is similar to our stone reported here, but with much weaker color change.

Figure 2. Left: Three LA-ICP-MS data points, calculated based on molecular percentages for pyralspite garnet, were plotted in a pyrope-spessartine-almandine ternary diagram (modified after Stockton and Manson, 1985). Refractive index and spectral boundaries were used to distinguish among the six proposed garnet gem species labeled in the diagram. Right: The same data points were further plotted in the pyrope-spessartine-almandine RI-SG diagram (modified after Deer et al., 1982) to validate the measured over-the-limits RI.
To understand why this spessartine garnet showed a color-change phenomenon, we collected an ultraviolet/visible/near-infrared (UV-Vis-NIR) spectrum (the visible portion of the spectrum is shown in figure 3), which was then used to quantitatively calculate the stone’s colorimetric coordinates (L*, a*, and b*; see table 2 at www.gia.edu/gems-gemology/summer-2019-labnotes-color-change-spessartine-garnet-icp-table2.pdf) under different lighting conditions. The strong absorption below 450 nm is caused by Mn2+ (R.K. Moore and W.B. White, “Electronic spectra of transition metal ions in silicate garnets,” Canadian Mineralogist, Vol. 11, No. 4, 1972, pp. 791–811). A wide absorption band centered at about 585 nm is caused mainly by V3+ (C.A. Geiger et al., “Single-crystal IR- and UV/VIS-spectroscopic measurements on transition-metal-bearing pyrope: the incorporation of hydroxide in garnet,” European Journal of Mineralogy, Vol. 12, No. 2, 2000, pp. 259–271), which produced two transmission windows: one in the blue-green part of the spectrum (figure 3, window A) and the other in the red (figure 3, window B). This was the cause of the color change in this spessartine garnet, as incandescent illumination highlighted the red transmission window and daylight-equivalent lighting highlighted the blue-green window. Color pairs under CIE D65 illumination (representing daylight-equivalent lighting) and CIE A illumination (representing incandescent illumination) were calculated and are shown in figure 3, above transmission window A and B. The darker color pair (top row), directly calculated from the measured UV-Vis-NIR spectrum, closely matched the dark appearance of the stone (again, see figure 1) with L*(lightness) around 14.5. It was the strong absorption generated by very high Mn and V concentration, along with the stone’s relatively large size, that produced a long light path length. To better observe the saturation and hue of the color pair, the authors changed the L*to 50 and reproduced the color pair with the same a*and b*values (bottom row). The hue difference of the color pair is easier to see with increased lightness.

Figure 3. In the visible absorption spectrum of the stone, transmission window A is centered at 510 nm, while transmission window B is between 630 and 650 nm. The strong absorption below 450 nm is caused by Mn2+; a wide absorption band between 550 and 650 nm is caused mainly by V3+. The stone had so much Mn that the detector of the instrument was saturated below 440 nm. Calculated color pairs, representing the color of the stone seen under CIE D65 illumination and CIE A illumination, are shown above the two transmission windows. The human eye is not color sensitive above 650 nm or below 420 nm (both represented in the graph by the gray color zoning). The transmission in these wavelength ranges cannot be perceived effectively.

One way to judge the quality of a color-change stone is to plot the color pair in the CIELAB 1976 color circle. Good color-change pairings show a large hue angle difference, small chroma difference, and large chroma values (Z. Sun et al., “How to facet gem-quality chrysoberyl: Clues from the relationship between color and pleochroism, with spectroscopic analysis and colorimetric parameters,” American Mineralogist, Vol. 102, No. 8, 2017, pp. 1747–1758). The color coordinates L*, a*, and b*(again, see table 2) of the stone under CIE D65 illumination and CIE A illumination were plotted in the CIELAB 1976 color circle in figure 4. The spessartine showed a low saturation under CIE A illumination.

Figure 4. In the CIELAB 1976 color circle, the color of the stone changes from medium saturated green under CIE D65 illumination to low saturated orangy red under CIE A illumination, with a hue angle difference of 79.11°, a chroma difference of 9.25, and a color difference of 15.82. Full sets of L*, a*, b* and RGB color coordinates are shown in table 2.
Color change has been reported previously in pyrope-spessartine (K. Schmetzer et al., “Color-change garnets from Madagascar: Variation of chemical, spectroscopic and colorimetric properties,” Journal of Gemmology, Vol. 31, No. 5-8, 2009, pp. 235–282), in pyrope (Z. Sun et al., “Vanadium- and chromium-bearing pink pyrope garnet: characterization and quantitative colorimetric analysis,” Winter 2015 G&G, pp. 348–369), and in grossular (Spring 2018 GNI, pp. 233–236). To the authors’ knowledge, this was the first color-change spessartine reported. @topic:1


Publish Year: 2017 Title: Tri-Color-Change Holmium-Doped Synthetic CZ Abstract: Figure 1. This 68 ct synthetic CZ shows three distinct hues in CIE standard illuminant F10 (left), CIE standard illuminant F9 (center), and CIE standard illuminant D65 (right). Photos by Robison McMurtry.
Colored yttria-stabilized synthetic cubic zirconia (CZ) has been an attractive diamond substitute since the late 1970s (R.T. Liddicoat and J.I. Koivula, “Synthetic cubic stabilized zirconia,” Summer 1978 G&G, pp. 58–60). The different colors seen in synthetic CZ are caused by the introduction of specific transition metal elements and rare earth elements (K. Nassau, “Cubic zirconia: an update,” Spring 1981 G&G, pp. 9–19). At this year’s Tucson Gem and Mineral Show, the authors obtained an interesting synthetic CZ rough that exhibited an unusual color-change behavior (figure 1). Unlike traditional color-change stones such as alexandrite, color-change corundum, and color-change garnet, this material did not exhibit different colors when illumination alternated between incandescent light and daylight conditions (approximated by CIE standard illuminants A and D65, respectively). Surprisingly, it showed three distinct hues in daylight/incandescent light (yellowish green), in fluorescent lighting corresponding to CIE standard illuminant F9 (green-blue), and in CIE standard illuminant F10 (purplish violet). One wafer with 3.32 mm thickness was polished and analyzed to understand this color-change phenomenon.

The wafer’s chemical composition was obtained using a Thermo Fisher iCAP Q ICP-MS coupled with a New Wave Research UP-213 laser ablation unit. Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) analyses were performed in the same spot where the spectroscopic data was collected. Based on its calculated chemical formula of Zr0.52Y0.45Ho0.02Hf0.01O1.79 (the formula is nonstoichiometric and calculated by forcing cations to 1 atom per formula), the wafer was a holmium-doped yttria-stabilized CZ (S. Gutzov et al., “High temperature optical spectroscopy of cubicholmium doped zirconia, Zr0.78Y0.21Ho0.01O1.90,” Physical Chemistry Chemical Physics, Vol. 9, No, 4, 2007, pp. 491–496). Holmium was the only detected chromophore, at a concentration of about 7780 ppma.

Visible spectra were collected with a Hitachi U-2910 spectrometer with a 1 nm spectral resolution at a scan speed of 400 nm/min. The wafer’s spectrum matched the holmium-doped CZ spectrum reported by Gutzov et al. (2007). The unusual color change under different illuminants can be qualitatively understood by examining figure 2. The violet and orange emission peaks of the F10 illuminant are not absorbed by Ho-doped CZ; however, there is significant absorption by holmium of the green emission peak for the F10 illuminant. This selective absorption of the F10 emissions creates a purplish violet color (figure 2, top). The F9 illuminant has more of a broadband emission, which is unaffected by the strong but narrow absorption by holmium of green light at 540 nm. This results in a blue-green color under F9 illumination (figure 2, middle). The D65 illuminant is essentially a broadband emission roughly corresponding to a black body irradiator at 6500 K. Under D65 illumination, a yellowish green color is produced because of the strong absorption of blue light by holmium (figure 2, bottom).

Figure 2. The UV-Vis-NIR absorption spectrum of holmium-doped
synthetic CZ is shown with the relative power distribution curves of
CIE illuminant F10 (top), CIE illuminant F9 (middle), and CIE
illuminant D65 (bottom).

Figure 3. In the CIELab 1976 color circle, the color of holmium-doped synthetic CZ with 10 mm light path length changes from yellowish green in CIE standard illuminant D65 to blue-green in CIE standard illuminant F9 to purplish violet in CIE standard illuminant F10. The hue angle differences are 148.61° between D65 and F10, 34.96° between D65 and F9, and 113.65° between F10 and F9. The chroma differences are 4.73 between D65 andF10, 15.52 between D65 and F9, and 10.79 between F10 and F9. In contrast, the hue angle difference and chroma difference between D65 and A are 3.37° and 5.79, respectively.
The wafer’s visible absorption spectrum was reflection corrected by subtracting the absorbance value at 850 nm, where no chromophoric absorption is expected, from values for every other data point along the rest of the spectrum. The reflection-loss-corrected visible spectrum can then be used to quantitatively calculate the color of this material at a wide range of path lengths and under different lighting conditions (Z. Sun et al., “Vanadium- and chromium- bearing pink pyrope garnet: Characterization and quantitative colorimetric analysis,” Winter 2015 G&G, pp. 348–369). There are large differences in the CIE L*, a*, b* color coordinates between D65, F10, and F9 (figure 3). One way to judge the quality of a color-change stone is to plot the color pair in the CIE 1976 color circle. Well-defined color-change pairings show a large hue angle difference, a small chroma difference, and high chroma values. The color coordinates of the material with a 10 mm light path length in D65, F9, and F10 were plotted in the CIE 1976 color circle shown in figure 3; calculated color panels for the illuminants were also placed alongside the faceted material (see below). The fact that the material shows three distinct hues in three different white lights makes it unique. @topic:10


Publish Year: - Title: Chasing the Rainbow: Australia Opal Fields Expedition Abstract: The authors have never met any other group as passionate about their work as the Australian opal miners. Photo by Andrew Lucas/GIA.

		Beware of the opal bug! It is a close kin to the love bug and, once bitten, there is no escape.

		—Len Cram, a Lightning Ridge “bush” scientist and world authority on Australian opals

	INTRODUCTION

	With the world's primary supply of black and boulder opal coming from its wild outback, Australia is synonymous with opal. Since the first recorded discovery of precious opal in the 1840s, its fabulous play-of-color has delivered excitement and delight to consumers all over the world.

	Chasing the Rainbow:Australia Opal Fields Expedition

	Journey with us into the Australian opal fields and see the passion in chasing the rainbow.

	In May 2015 GIA sent a group of field gemologists to the southern hemisphere to explore some famous opal fields, where they were impressed by the tenacious optimism of the miners and learned extensively about this breathtaking gemstone. The team included GIA field gemologists Vincent Pardieu and Andrew Lucas, G&G technical editor Tao Hsu, assistant field gemologist Victoria Raynaud, and field cameramen Didier Gruel and Didier Barriere Doleac.

	This exceptional black opal is called supernova and has a rare star pattern in its dramatically
	bright play-of-color. It also has a truly black background color. Photo courtesy Cody Opal.

The National Opal Collection in Sydney features a full 3-meter-long skeleton of an opalized pliosaur. Along with precious opals, opalized prehistoric fossils are the pride of the nation. Photo by Tao Hsu, courtesy Cody Opal.

	THE JOURNEY

		Between latitudes 22° and 31° South, and extending from longitude 145.30° across the Queensland and South Australian boundaries into the heart of the interior desert land, stretches a tract of country which presents many strange problems to explorers and others interested in the study of the earth’s formation.

		—Robert M. Macdonald, 1904

The GIA team from left to right: Didier Barriere Doleac, Tao Hsu, Andy Lucas, Vincent Pardieu, Victoria Raynaud, and Didier Gruel. Photo by Terry Coldham/GIA.

	Taking off from Sydney, the GIA crew traveled to North New South Wales and Queensland
	to explore four world-famous opal fields. Map adapted from Anthony Smallwood, 2014.

	The opal journey started at Lightning Ridge, New South Wales, the household name for black opal. In Lightning Ridge the team met multiple opal miners, cutters, and researchers who shared their techniques, experience, and passion for the opal industry. The authors also visited many characteristic opal shops and looked at the finished loose stones and jewelry pieces. Then we headed northwest to visit boulder opal fields. We spent one full day in each of the following fields: Koroit, Yowah, and Quilpie. Both open-pit and underground mines were covered by the team. (Please note that the Australian miners refer to open-pit operations as open-cut operations, which is reflected in the upcoming videos of the miners.) Finished boulder opal products were checked and recorded as well. Famous opal fields such as White Cliffs, Andamooka, and Coober Pedy along the southern and southwestern margin of the Great Artesian Basin were not covered in this trip. More detailed information about each location the GIA group visited will be provided in following Australian opal series articles.

	Vincent Pardieu selects black opal specimens from a mine run in Lightning Ridge,
	Australia. Photo by Victoria Raynaud/GIA.

Well-known opal expert Andrew Cody hosted the GIA crew in his opal store in Sydney. The store highlights Australia’s National Opal Collection. Field gemologist Andrew Lucas was impressed by the Cody brothers’ collection and their passion. Photo by Tao Hsu/GIA.

	THE OPAL FIELDS

Terry Coldham, with 50 years of experience in the Australian gem industry, graciously agreed to become our expert guide, taking us through the Australian opal and sapphire fields and sharing his wealth of knowledge. Photo by Vincent Pardieu/GIA.

	Australian opal is predominantly found in sedimentary rocks within the Great Artesian Basin. The Great Artesian Basin is the largest artesian basin on this planet and the main “water tank” that supplies inland Australia. The basin is the remnant of an inland sea filled with sediments. Some volcanic opals have been recovered, but production is very limited compared to sedimentary opal. Although the chemistry and the microscopic structure of opal have been well analyzed, the formation of this gemstone is still much debated within the research field.

	Artesian bores are very common in the Great Artesian Basin. They provide water for both
	residents and visitors. Along with opals, hot springs attract many tourists.

	Multiple models have been published with supportive evidence to demonstrate how opal formed. One certainty is that not all opal formed in the same way. Supply and transportation of silica, space for growth, sedimentation conditions, and ion exchange processes are some critical questions to be answered before any definitive model is constructed. During this visit we also found that although these opal fields have many things in common, such as Jurassic- and Cretaceous-period sedimentary host rocks, each one has its own characteristics.

GIA field gemologist Andrew Lucas interviews opal miner Mark Moore in his open-pit opal operation in Koroit. The geology is much easier to see in a large open pit like this. Photo by Tao Hsu/GIA.

	Our first stop is Lightning Ridge, synonymous in the gem industry with top-quality black opal. The town is located in northern New South Wales and close to the border between New South Wales and Queensland. Geologically, Lightning Ridge is situated in the Surat Basin, part of the Great Artesian Basin. The sedimentary host rocks are more or less horizontal with no deformation. Black opal occurs as nobbies and as seams. The stones are generally found between 6 to 18 meters below the surface. Also amazing in this field are the extraordinary opal fossils of the Cretaceous age. These fossils are considered a national treasure and are well preserved in the Australian Opal Centre for both exhibition and paleontological research. Known for its rich history of black opal mining, mineral water spas, and unique Australian outback lifestyle, Lightning Ridge has long been a tourism hot spot, with more than 90,000 visitors per year.

View Gallery

	Lightning Ridge Opal Field Gallery

	To the northwest of Lightning Ridge are the Queensland boulder opal fields. Boulder opal from Queensland has very bright play-of-color, which makes these stones extremely appealing. The stone is called boulder opal because it is always attached to its host ironstone. Though the sedimentary host rocks are very similar to those in Lightning Ridge, the opal occurs mainly in ironstone concretions or as pipes instead of nobbies. Seam opal can sometimes be found in Queensland fields. Though local miners give the ironstone concretions different nicknames, such as “nuts” or “lily pads,” based on their different shapes, they bear the same concentric internal structure. Opal can be found as the kernel of the “nuts,” between the concentric layers of ironstone or on the surface of the concretions. Certain opalized fossils were also recorded in this area, with plant fossils commonly seen.

	There are over a dozen boulder opal fields in Queensland. Some of them are still active
	while others are exhausted for commercial mining.

	There are more than a dozen boulder opal fields in Queensland; the GIA team visited Koroit, Yowah, and Quilpie. The Koroit opal field was first discovered in 1897, and the most recent mining activities started in 1972, when consumers regained interest in boulder opal and sales became more profitable. The mine operated by Mark Moore has both a large-scale open pit and a small-scale underground shaft. The stones from this mine are quite stunning, with a range of quality. Today Koroit is unquestionably one of the main boulder opal suppliers in Queensland.

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	Koroit Fields Gallery

	Yowah is a small town southwest of Koroit. The name Yowah is from Yowah Creek, where people formed a large horse station in 1872. The small opal field was first discovered around the same time. This mining area is famous for its “Yowah nuts”—precious opal sometimes occurs as the kernel of ironstone nuts. The authors observed both large-scale mechanical mining and fossicking in this field. With necessary supply and food providers, plus the permanent hot spring bores, the town has become a popular tourism and fossicking destination.

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	Yowah Boulder Opal Field Gallery

	Heading northwest from Yowah, we arrived at Quilpie. The town was officially granted the township in 1917, while opal was discovered in this area around 1885. It serves as a center for the southern Queensland opal industry and is a gateway to multiple historic boulder opal mines. Mining activities in this field all cluster to the west and north-northwest of the town. Here you can find some of the more productive mines in recent times. Known as the “home of boulder opal,” the area is the largest producer of this variety in the world. Now, like many other famous opal towns, Quilpie is also a tourist- and fossicker-friendly place. The group visited an opal shop in town and a large open-pit mine north of Quilpie, where the exposed ironstone nuts range from centimeters to over a meter in diameter. The mine owner also cuts and polishes some of their production, and finished product was shown to the authors.

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	Quilpie Gallery

	THE STONES

	Opal is an amorphous form of silica, and precious opal shows the rainbow colors we call play-of-color, caused by the diffraction of light. Precious opal is rare as its structure is composed of tiny silica spheres tightly packed in a three-dimensional grid. Light is broken up into the colors of the rainbow by the tiny voids between the spheres. To give an idea of the size of the spheres, those that are 0.20 microns have spaces between them that diffract the light to cause a blue play-of-color; 0.25 microns, a green color; and 0.32 microns, a red color. These tiny spheres that are responsible for play-of-color require an electron microscope of at least 30,000X magnification to see them.

Opal cutter and carver Justine Buckley holds a 92-carat Lightning Ridge black opal that she cut. Photo by Andrew Lucas/GIA.

	The Australian opal miners, cutters, and dealers all repeated one important attribute of opal: it is the only stone that can show every color of the rainbow. Our trip focused on the areas that produce black opal and boulder opal, both types of opal famous from Australia. Both types possess a range of appearances; in fact every stone is unique with its combination of colors. All the members of the expedition found opal to be a captivating if not mesmerizing stone.

The day we visited the opal processing area, Frederic Mallock was processing several days’ mining production, and he found this striking black opal while we watched. Photo by Andrew Lucas/GIA.

	Black opal refers to opals that have a dark bodycolor when viewed from above. They can be almost transparent to opaque, with an endless variety of play-of-color. Black opal is considered the rarest and most valuable opal. Boulder opal has thin veins of precious opal in the host rock the opal formed in, which is usually ironstone. The opal forms as infillings in the cracks and spaces of the ironstone. Boulder opal is usually cut free-form and wavy to follow the contours of the opal.

This black opal in sandstone is referred to as a nodule or nobby. Photo by Robert Weldon/GIA, courtesy Cody Opal.

	Vincent Pardieu displays a classic example of a Koroit boulder opal. Photo by Victoria
	Raynaud/GIA.

	Add to the appearance equation the pattern of the play-of-color, the underlying bodycolor, the brightness of the rainbow colors, the number of colors, the dominant rainbow colors, the thickness of the seam of play-of-color or color bar, the depth of the transparency, and the shape of the stone, and it is easy to see why each opal is unique and why opal is considered by many gem experts to be the most complex stone to grade. While market preferences determine the values of different opal appearances, opal is truly a personal stone with a beauty that is very subjective.

	Perhaps one of the best summations of opal was given in the first century ad:

		For in them you shall see the living fire of the ruby, the glorious purple of the amethyst, the sea green of the emerald all glittering together in an incredible mixture of light.

		—Pliny the Elder

View Gallery

	Black Opal Gallery

View Gallery

	Boulder Opals Gallery

	THE PEOPLE

Opal miners like Colin Stelzer have an adventurous nature that is contagious, as geologist Tao Hsu discovered after taking a flight in an ultralight plane to view the mining terrain from the sky. Photo by Andrew Lucas/GIA.

	The striking impression when conversing with Australia opal miners is their fierce sense of independence. These are people who love their freedom and the ability to live their lives as they see fit. All of the miners we spoke to said they could never live any other way. These men and women reminded us of the U.S. cowboys who lived in the 1800s, forging their way west. The hardships and risks involved in their lifestyle seem trivial compared to that of the Australian opal miners.

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	Australian Opal Miners Gallery

	The companies mining opal are really individuals. Often a company is a partnership with just a couple of people working a claim, or in some cases just one person. If there are employees, there are just a few. This is a world of the rugged individual. Miners not only mine the opal themselves but also keep the equipment going, make repairs, and handle everything necessary to maintain the operation.

	Opal miner Colin Stelzer proudly displays a nut from his family’s mine near Quilpie that
	might contain boulder opal. Opal mining is often a partner or family operation and often
	passed down from father to son. Photo by Andrew Lucas/GIA.

	Another factor that drew these people to the search for opal was the thrill of finding beautiful opals. Even with the gamble, the risks, and no assurances, the hope of a major find is strong enough to keep them going through the tough times. One miner explained that there was a four-year period in which he found no opal, and continuing was extremely difficult. Then he discovered a significant pocket of black opal in his mine, and that rush of adrenaline made it all worthwhile. There is no guarantee of finding pockets of valuable opal, and experience and knowledge greatly contribute to success, but perseverance is the key factor—and of course luck.

		I have known people that have been here for 50 years and never found more than $1,000 and people that have been here for ten minutes and found millions.

		—Kim, Lightning Ridge black opal miner

	All the opal miners conveyed this same feeling of euphoria when finding opal. Hope is the universal feeling among the miners—the hope of making the next big find and hitting that pocket of top-quality opal that will make all the hard work and patience worthwhile.

		Finding an opal is like an injection of endorphins…it is like Mother Nature teasing you, saying, ‘come on, a little bit further; a little bit further anything can happen. Your fantasy and your dreams might just come true just a few more inches.’

		—Frederic Mallock, Lightning Ridge black opal miner

	Frederic Mallock began helping his father mine opal when he was around 10 years old. He said the excitement is still there, but it is a different excitement. In the beginning it was like a fantasy. Now that he is seasoned with over 45 years of experience, he knows what is possible, but the thrill of discovery is still there, and the passion is as strong as ever. All the opal miners we met, whether black opal miners or boulder opal miners, said there was no other job in the world they would want. None of them could see themselves working in a corporation, sitting in an office, or being told what to do by anyone. All the miners gave a similar answer:

		[Expletive] no, mate; it is the best. Hey, I am my own boss. Nobody tells me what to do, when to do it, how to do it, and we are actually in with a chance the fantasy might come true.

		—Frederic Mallock, Lightning Ridge black opal miner

Frederic Mallock operates his opal digging machine to scrape away at the walls of the mine. Opal miners have an incredible drive. Besides mining, operating equipment, processing, sorting, and exploring, he and his partner also maintain the equipment. Photo by Andrew Lucas/GIA.

	Mark Moore mines boulder opal in Koroit from March through November, a couple of months longer than most, as the temperature reaches 48 degrees Celsius (118.4 degrees Fahrenheit) in the summer, heating people and machinery, with constant droughts. In the ingenious and independent spirit of opal miners, Moore has created a comfortable and harmonious environment in the outback. He has a greenhouse for growing vegetables, a water recycling system, and even a couple of bathtubs outside that are propped up so hot coals can be placed underneath to make homemade hot tubs.

Mark Moore makes the best out of his environment at his mining camp in the outback by incorporating a greenhouse for vegetables, a satellite dish, water recycling, and even homemade hot tubs. For a barbecue Moore goes out into the bush and hunts game like wild boar. Photo by Andrew Lucas/GIA.

	Many of the miners we met also cut their opal and sell the finished stones as well as rough. Some have even entered the retail business, opening shops in the towns near their mines, such as Lightning Ridge, Quilpie, Cunnamulla, and Yowah. Justine Buckley in Lightning Ridge is involved in not only mining but also cutting the opals, designing and creating jewelry, and even owning a retail store. This mine-to-market approach allows miners to maximize income by catering to wholesale markets as well as tourist markets, depending on which is stronger. In fact several miners we met in the black opal and boulder opal mining areas have adopted this business model.

Mark Hodges proudly stands outside his store, Sunrise Opals, in Quilpie. For Mark and his wife, Sandy, the artistic gratification of cutting opal and creating jewelry led to a retail business to sell their creations. Photo by Andrew Lucas/GIA.

	During our trip the free spirit of the Australian opal miners was best envisioned during a visit to Eric Stelzer’s boulder opal mine. Both Eric and his son Colin are avid ultralight pilots. Colin took the expedition group up one by one, flying over the mining area so they could photograph and better understand the nature of the deposit. This flight in the simplest of machines symbolized the uncontained spirit and minimalist lifestyles of the Australian opal miners.

Boulder opal miner Colin Stelzer’s passion for ultralight planes symbolizes the Australian opal miners’ independence, free spirit, and passion for adventure. Photo by Andrew Lucas/GIA. @topic:13


Publish Year: 2013 Title: Internal Texture and Syngenetic Inclusions in Carbonado Abstract: Carbonado is a black or dark brown cryptocrystalline aggregate of diamond. Its age ranges from 2.6 to 3.8 Ga (billions of years), according to lead isotopic composition. Carbonados have been found only in alluvial placer deposits, such as those in Brazil and Central Africa, and never in kimberlite. Many hypotheses, including non-kimberlitic, crustal origin of carbonado were proposed by previous researchers. Analysis of internal texture and syngenetic inclusions is important to understanding the genesis.

		Carbonado samples were collected from alluvial placer deposits of the Macaubas River basin in the Brazilian state of Minas Gerais and the Ubangi River basin in the Central African Republic. They were dark or nearly black, with a smooth and shiny surface. The samples contained pores ranging from a few hundred nanometers to a few micrometers. Secondary electron images revealed a typical polycrystalline structure, which showed fine-grained texture with irregularly shaped diamond grains averaging 5 to 15 µm. Grain boundaries were in irregular, zigzag patterns. Numerous pores, up to 20 µm, were found inside grain boundaries. They were usually filled with postgenetic minerals such as kaolinite, flurencite, and quartz. Dislocation lines were also observed within some diamond grains. The pole figures suggested that crystallographic orientations of these grains were quasi-random.

		Syngenetic inclusions ranging from 10 to 50 nm were identified using the combined FIB/TEM technique: garnet, apatite (including fluorapatite), phlogopite, silica, Ca-Mg-Sr- and Ca-Ba-carbonates, halides (sylvite, KCl, and bismocolite, BiOCl), native nickel and metal alloys (Fe-Ni, Cr-Fe-Mn, and Pb-As-Mo), oxides (FeO, Fe-Sn-O, TiO2, SnO2, and PbO2), Fe-sulfides, and fluid inclusions. An intergrowth of fluorapatite, phlogopite, and silica was also observed. Almandine-pyrope garnet inclusions with silica-enriched amorphous rims were confirmed. Fluid inclusions contained Si, Al, Fe, O, Ti, Ca, S, Cl, K, and carbonate. These fluid inclusions suggested the carbonados were formed in a chloride-rich environment. Crystal inclusions were not pressure-indicator minerals. Instead, they were stable in a wide range, from crust to lower mantle, except bismocolite, which could only be formed in the crust. Although this whole inclusion assemblage was possibly of crustal origin, conclusive research is still needed. The authors propose that these samples were crystallized and grown in one stage, which was followed by sintering. This hypothesis could be confirmed by comparison with one-stage growth process of a polycrystalline diamondite.

Abstracted by Kyaw Moe @topic:2


Publish Year: - Title: Eunice Miles (1917–1997) Abstract: Shortly after Eunice Miles became the first female gemologist at GIA’s New York lab in 1953, two dealers brought in an important diamond they wanted “the boys” to see. After examining it under the microscope, the gentlemen invited Miles to take a look. She did—and immediately spotted a pinpoint inclusion they had missed. After that, she became known as the “Pinpoint Girl.”

Miles’s fascination with gemstones began early, when she played with her grandmother’s gem and mineral collection as a child. She studied geology in college during the 1930s and approached Dr. Edward Wigglesworth, then director of Boston’s New England Museum of Natural History and later head of GIA’s East Coast office, to learn more. Although women “simply were not accepted in the field,” as she recalled, Wigglesworth took her on as an assistant and taught her mineralogy and gem testing.

During the 1950s, Miles helped establish GIA’s reputation with the New York diamond trade, and clients came to recognize her initials on diamond grading reports. Identification became her area of expertise as the flow of diamonds to the lab increased. In response to sophisticated new diamond coatings, she developed an optical technique for detecting them with magnification. Miles was cited in the U.S. Department of Mines’ 1963 annual report for her work, and the Federal Bureau of Investigation later used her data to arrest a major dealer of fraudulently coated diamonds.

The Manhattan chapter of the GIA Alumni Association honored the pioneering “Grande Dame of Gemology” in 1989 when it created a scholarship in her name. @topic:6


Publish Year: - Title: GIA Field Gemologists seek Ruby, Sapphire, and Spinel in Mogok, Myanmar Abstract: Seeking Mogok’s Hidden Gems

	Venture into Mogok’s deepest mines with GIA field gemologists.

	This video takes you deep underground with GIA’s Field Gemologists Vincent Pardieu and Dr. Aaron Palke as they explore the geology of Mogok’s ruby, sapphire, and spinel deposits.

	Mogok’s unparalleled reputation as the source of fine gemstones goes back more than 800 years. The Mogok mining area is about 400 miles (650 km) north of Yangon in a densely vegetated, mountainous area rising to 7,700 feet (2,347 meters) above sea level.

	This video shows the lengths GIA’s field gemologists go to in order to secure gemstone samples for research and provides a rare glimpse into some of Mogok’s deepest underground hard-rock mining operations. It documents their sometimes perilous descent down handmade ladders and via ropes and pulleys into the depths of some of these famous mines. At one point the intrepid gemologists are 1,200 feet (365 meters) below the surface. According to Pardieu, that deep descent into the mining operation in the Kadoke Tad area—where the group witnessed ruby mining—was the expedition’s highlight.

	Later, the markets and temples of Mogok township demonstrate the romantic allure and timeless appeal this location and its people have for so many gemologists and gem dealers. “There’s something absolutely amazing about Mogok,” offers Pardieu. “This place produces the best quality ruby, the best quality sapphire, the best quality spinel, the best quality peridot, probably in the world.”

	This GIA Field Expedition (FE62) took place in June 2014. Besides Pardieu and his cameraman Didier Gruel, the participants were two geologists, Dr. Gaston Giuliani, Director of Research at the Institute of Research for Development (IRD) in Nancy, France, and Dr. Aaron Palke, post-doctoral research associate at GIA in Carlsbad. @topic:9


Publish Year: 2020 Title: Blue Apatite in Pyrope-Spessartine Garnet Abstract: Figure 1. This 5.33 ct red pyrope-spessartine garnet was faceted by the author to display the unusual blue apatite crystal within. Photo by Diego Sanchez.

The author recently had the opportunity to examine and facet a piece of garnet rough. The garnet, reportedly from Madagascar, was acquired from gem cutter and dealer Desmond Chan of Los Angeles. The rough was selected for the unusual blue apatite crystal nearly reaching the surface. Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) chemical analysis indicated the rough to be a pyrope-spessartine variety. When orienting the stone in preparation for faceting, the author wanted the apatite inclusion to be the main focus of the gemstone. After slow and careful execution, a cut-cornered mixed-cut faceted gem was achieved, with the apatite eye-visible just under the table facet (figure 1). Oblique fiber-optic illumination was used to observe the world inside the gemstone, revealing a scene consisting of the blue euhedral apatite crystal paired with numerous iridescent intersecting needles of rutile (figure 2). This is one of the most unusual inclusions the author has seen in a garnet, and it is also notable as the gem was faceted to showcase the inclusion rather than hide or remove it.

Figure 2. A blue apatite crystal associated with intersecting iridescent needles was showcased. Photomicrograph by Jessa Rizzo; field of view 2.90 mm. @topic:1


Publish Year: 1983 Title: Kashmir Sapphire Abstract: The unique beauty of gem sapphires from Kashmir has brought fame to a locality about which little has been reported in recent years. After an initial burst of activity 100 years ago, the production of these gemstones has slowed to a trickle and the majority of the corundum from these mines today is of industrial grade. Despite evidence of other gem mineral occurrences in the area, difficult terrain and political factors have impeded their exploitation. This article, the result of an expedition to the deposits in 1981, chronicles the history of the Kashmir mines, describes the characteristics of the sapphires found there, and examines the outlook for the future of this area. @topic:2


Publish Year: 2015 Title: Purple Scapolite Abstract: Figure 1. These two brownish purple specimens, a 1.58 ct oval and a 2.95 ct cushion, were identified through gemological testing as scapolite. Photo by Gagan Choudhary.

Two brownish purple faceted specimens (figure 1) were submitted for identification at the Gem Testing Laboratory, Jaipur, India. The 2.95 ct mixed cushion measured 9.95 × 8.05 × 5.88 mm, while the 1.58 ct mixed oval measured 9.07 × 7.08 × 4.46 mm. Both were relatively clean to the unaided eye. Based on their color, they were thought to be spinel, but testing soon proved otherwise. Testing yielded the following gemological properties: optic figure—uniaxial; RI—1.549–1.559; birefringence—0.010; and hydrostatic SG—2.63. The material fluoresced a weak orangy red under short-wave UV and was inert under long-wave UV. An absorption band was observed in the yellow-green region using a desk-model spectroscope. In addition, both samples displayed strong dichroism (figure 2) with deep saturated and pale purple colors along the “o” and “e” rays, respectively; this also influenced their face-up color. Under magnification, growth zones and two-directional cleavage planes intersecting at almost 90° were visible. The cleavage planes also contained some fine dendritic films; additionally, the oval specimen had an unidentified brown crystal.

Figure 2. The scapolite specimens displayed intense dichroism (shown here in the cushion), with a deep saturated purple along the o-ray (left) and pale purple along the e-ray (right). Photos by Gagan Choudhary.
These gemological properties were consistent with scapolite. Raman spectroscopy confirmed this, showing the characteristic peaks for scapolite at approximately 260, 296, 359, 418, 455, 534, 771, 993, and 1093 cm–1. The Raman spectra suggested the specimens belonged to the marialite end of the meionite-marialite solid solution series of the scapolite group (see rruff.info); this was supported by their RI and SG values (R. Webster, Gems: Their Sources, Descriptions and Identification, 5th ed., rev. by P.G. Read, Butterworth-Heinemann, Oxford, UK). Polarized absorption spectra (figure 3) revealed a broad absorption centered at approximately 550 nm in both specimens. The intensity of this absorption was stronger in the o-ray direction, while a weak hump at about 630 nm was also present in the e-ray direction. Such absorption bands, associated with Fe3+ ions and producing purple coloration, have been reported in sugilite (Spring 1995 GNI, pp. 66–67); however, additional Fe3+ features at approximately 350–365 and 410–420 nm were absent in both the “e” and “o” rays of those specimens. Qualitative EDXRF analysis revealed the presence of Al, Si, K, Ca, Fe, Br, and Sr. Mn is a common impurity resulting in purple coloration of stones such as kunzite or some sugilites, but it was not detected in these specimens. On the basis of absorption spectra and elemental analysis, the purple color of these scapolites appears to be caused exclusively by an Fe impurity.

Figure 3. Polarized UV-Vis spectra of the cushion-cut scapolite (shown here in the
cushion) displayed Fe-related absorption at approximately 550 nm, which is responsible
for the purple color of these specimens.
Purple scapolite is known from many localities such as Myanmar, Tanzania, and Tajikistan, but the client did not know the source of these stones. Although we have seen many purple to violet scapolites in the past, these specimens were different because of their brown color component, reminiscent of spinel. @topic:1


Publish Year: 2015 Title: Orange Faceted Eosphorite Abstract: Figure 1. This 5.85 ct orange mixed cut was a rare faceted eosphorite. Photo by Robison McMurtry.

The Carlsbad laboratory recently examined a 5.85 ct transparent orange oval mixed cut for identification services (figure 1). Standard gemological testing showed an RI of 1.640 to 1.667; the hydrostatic SG was 3.12. The stone showed yellow and reddish orange pleochroism. Fluorescence was inert to long-wave and short-wave UV radiation. The most distinctive internal characteristic, revealed by microscopic examination, was the presence of multiphase inclusions (figure 2), suggesting a formation process with the presence of water, such as pegmatitic and hydrothermal processes.

Figure 2. Multiphase primary fluid inclusions are seen in the eosphorite, indicating a
pegmatitic or hydrothermal formation process. Photomicrograph by Nathan Renfro;
field of view 1.26 mm.
Raman spectroscopy confirmed that the stone belongs to the childrenite-eosphorite mineral series (figure 3), with intense peaks observed at 970 and 1011 cm–1. These peaks are attributed to the P-O (phosphorus-oxygen) stretching vibrations (R. L. Frost et al., “Vibrational spectroscopic characterization of the phosphate mineral series eosphorite-childrenite-(Mn,Fe)Al(PO4)(OH)2·(H2O),” Vibrational Spectroscopy, 2013, Vol. 67, pp. 14–21). This mineral series has a stoichiometric formula (Mn,Fe)Al(PO4)(OH)2·(H2O). Visible absorption spectroscopy revealed that the stone’s orange color results from the combination of Fe and Mn (M.A. Hoyos et al., “New structural and spectroscopic data for eosphorite,” Mineralogical Magazine, 1993, Vol. 57, pp. 329–336).

Figure 3. Raman analysis of the eosphorite in the 2000–200 cm–1 range showed a typical
spectrum of phosphate oxyanions. The 970 and 1011 cm–1 peaks are assigned to the P-O
stretching vibration, while the 1038 and 1055 cm–1 peaks are attributed to the PO3–4
stretching vibration. The 405, 473, 561, 595, and 618 cm–1 peaks are associated with
the PO4 and H2PO4 bending modes.
Energy-dispersive X-ray fluorescence (EDXRF) analysis revealed a composition of 25.10 wt.% Al2O3, 31.74 wt.% P2O5, 15.46 wt.% MnO, 11.47 wt.% FeOtot, 0.49 wt.% MgO, 0.25 wt.% CaO, and 15.50 wt.% H2O (water weight percent is assumed from references). The stone contains 55.3 mol.% eosphorite and 40.5 mol.% childrenite. The calculated formula is
(Mn0.48Fe0.35Ca0.01Mg0.03)(Al)1.09(P0.99 O4)(OH)2·0.91(H2O), which indicates an intermediate member of the childrenite-eosphorite series with predominance of the Mn phase. As a result, the stone should be classified as eosphorite.

Eosphorite is the manganese-rich end member of the childrenite-eosphorite series, formed worldwide in pegmatites (T. J. Campbell and W. L. Roberts, “Phosphate minerals from the Tip Top mine, Black Hills, South Dakota,” Mineralogical Record, 1986, Vol. 17, pp. 237–254) or by hydrothermal phosphatization of metasediments and associated with the intrusion of granites (R. S. W. Braithwaite and B. V. Cooper, “Childrenite in South-West England,” Mineralogical Magazine, 1982, Vol. 46, pp. 119–126). This was the first faceted eosphorite examined by GIA’s Carlsbad laboratory. @topic:1


Publish Year: 2019 Title: Boulder Opal Mining with Rod Griffin Abstract: Figure 1. The Elusive mine in Koroit, Queensland, is known for boulder opal with the light pattern of color seen here. This stone fits in two hands (its weight is unknown). Photo by Kevin Schumacher, courtesy of Rod Griffin Boulder Opals.

At the AGTA show, Rod Griffin (Rod Griffin Boulder Opals, Silverado, California, and Queensland, Australia) told us that the world market for all types of opals continues to be strong, but Australia’s opal industry is shrinking due to the costs, challenges, and changing regulations of mining. He also cited recent flooding in Queensland as a challenge; opal mining in Australia has traditionally been difficult due to severe weather and rugged terrain. At the 2018 show, we heard that production of Australian boulder opal (figure 1) was low, with fewer than 30 people mining it in Queensland.
Griffin began mining opal in 1960 with a borrowed jackhammer and a lighting plant, in Andamooka, South Australia, 600 km (~372 miles) north of Adelaide. His methods have evolved considerably in the decades since. Along with standard equipment such as bulldozers, drills, and excavators, he recently began using gamma-ray logging for prospecting, and he will add drone magnetometer surveys and subsurface radar this year.
Mining is in Griffin’s blood. His great-great grandfather worked in South Australia’s Burra copper mines in the 1800s. Griffin’s own introduction to mining was at his uncle’s opal operation in northern South Australia. His uncle, who began with six camels and a scraper, eventually had one of the first bulldozers used in opal mining.
Griffin’s first find, at Andamooka, was black opal matrix in the bulldozer ramps. In 1970 he found more, in the 17 Mile Field in Coober Pedy. In 1976 he sold $400 (~$1,800 in 2019) worth of white Coober Pedy opal and boulder opal, bought a squareback Volkswagen, and traveled around the United States selling opal. He first exhibited in Tucson in 1977, at the Pueblo Inn (now the Riverpark Inn). “From that day on, I’ve been working all my life in opal,” he said.
Since then Griffin has mined in New South Wales—where he was the first to bring a tumbling machine to White Cliffs and to use a drill in the Sheepyard field at Lightning Ridge—and South West Queensland, where he and a friend found success using an excavator for the first time. His current operations are in South West Queensland, where he owns the 40-acre Elusive mine in Koroit and will be prospecting west of Quilpie this year.

Figure 2. This 245 ct boulder opal came from an open cut in the Elusive mine. The flame-like pattern is unique to Elusive. Photo by Kevin Schumacher, courtesy of Rod Griffin Boulder Opals.
People thought Griffin was crazy when he bought the Elusive mine in 2013–it was said to be depleted after more than a hundred years of mining. But he found opal 22 feet below ground and has been finding it at 22 to 25 feet for the last several years. The mine is known for boulder opal with the light pattern of color seen in figure 1. Elusive also produces boulder opals with a flame-like pattern (figure 2), which Griffin said is unique to this mine. He added that because the stones were found at a shallow depth and the area is dry, they are stable and will not craze or crack.

	Rod Griffin talks about his background in opal mining and his plans for mining in Quilpie this year.

In 2017 Griffin worked with two geologists to explore the Elusive mine using gamma-ray logging, which measures naturally occurring radiation in the ground to determine the potential presence of opal. According to Senior and Chadderton, microscopic lattices of silica spheres that produce precious opal’s play-of-color contain radioactive elements (“Natural gamma radioactivity and exploration for precious opal in Australia,” The Australian Gemmologist, No. 23, 2007, pp. 160–176). Gamma-ray logging of drill holes and open-cut mines has detected slightly higher radioactivity around opal deposits and led to new discoveries of opal in Queensland and New South Wales. At Elusive, it was determined that at the current rate of mining, at least seven years’ worth of reserves remains. Later in 2017, in several areas of the mine that had previously been explored without success, gamma-ray logging led to the detection of 1,230 opalized specimens, 30 of which were gem quality.
Griffin said this year he will use gamma-ray logging in prospecting 200 miles west of Quilpie; he will also use drones and subsurface radar for the first time. The drones will be fitted with magnetometers and flown a few feet above ground to measure magnetism and locate ironstone anomalies. Subsurface radar will determine the composition below the ground. Regulatory agency permitting has been secured for the property, and an indigenous land use agreement is in place. But Griffin said there has been a delay in the landowner acknowledging a standing agreement with the miners; he has seen more challenges in obtaining the agreement of all involved parties in recent years.
“There are easier ways to make money,” Griffin said. “But I actually feel that I’m in heaven at the moment, doing what I want to do, because I think I found my peace in life.” @topic:13


Publish Year: 2020 Title: Interesting “Egg” in Rock Crystal Quartz with Rutile Abstract: Rutile needles extending outward from epigenetic growth in rock crystal quartz. Photomicrograph by Nathan Renfro; field of view 8.81 mm. Courtesy of Mike Bowers.

The micro-world of gemology is fascinating and often mimics scenery, landscapes, or, in this case, food. Recently the authors examined a natural rock crystal quartz that showed needles piercing a yellow and white circular inclusion (see above). The inclusion mimicked a fried egg and was seen during microscopic examination using fiber-optic lighting. The “egg” was actually an example of epigenetic residue surrounding a rutile needle trapped in a crack within the host crystal. Here the rutile, a mineral composed primarily of titanium dioxide (TiO2), is a syngenetic inclusion, having formed at the same time as the host quartz crystal, and the “egg” formed its circular shape after the rutile and quartz growth stopped. The epigenetic residue in this stone results from secondary fluids that enter surface-reaching fractures (see descriptions and images of inclusions in quartz in E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 2, 2005, Opinio Publishers, Basel, Switzerland, p. 541). Although quartz is relatively common as a host material, it is often an excellent source for unique mineral inclusions and, with this particular crystal, a fun novelty inclusion. Epigenetic residues in gems and crystals not only provide for interesting inclusion scenes, but they can also help determine growth phases and possible treatments. @topic:3


Publish Year: 2022 Title: A Type of Multi-Colored Quartz with Oriented Inclusions, Reportedly from Brazil Abstract: Figure 1. Multi-colored quartz traded in the Donghai jewelry market in Jiangsu Province, China. Photo by Qingfeng Wu.
A special quartz called “Auralite 23” in the Chinese trade has recently appeared in the Donghai jewelry market in Jiangsu Province (figure 1). Sellers claim the material is from Brazil. The quartz is very similar to amethyst from Minas Gerais, Brazil (B.M. Laurs and N.D. Renfro, “Amethyst from Brazil with interesting inclusion patterns,” Journal of Gemmology, Vol. 35, No. 6, 2017, pp. 468–469).

Figure 2. A: External characteristics of a piece of rough “Auralite 23” quartz measuring 8.2 × 5.5 × 3.7 cm. Well-developed rhombohedrons can be found on one side of the quartz, and the other side displays an uneven pyramidal shape with parallel striations. B: Five color zones and substantial oriented inclusions. C: Golden “broom-like” inclusions form a beautiful independent zone. D: Alternating purple and red zones. Photos by Zhuoxuan Li.
Four color zones (purple, red, greenish gray, and a second purple zone) are displayed when observed along the threefold axis. Sometimes, a separate golden zone can be formed (e.g., figure 2, B and C). The purple and greenish gray zones in the upper part of figure 2D are well defined, while the red and purple zones in the lower part show alternating growth bands. After cutting, substantial oriented inclusions can be found in each color zone. Golden “broom-like” inclusions observed in the purple zones are regularly distributed along the growth direction. Greenish gray horsetail-like inclusions are found in the middle of the quartz. In addition, red platelet inclusions appear in the red zone (figure 3). Notably, the platelet inclusions are seemingly restricted to this red zone and thus generate an agate-like zoning.

Figure 3. Three representative solid inclusions in the multi-colored quartz. A golden “broom-like” inclusion in the purple region (A), greenish gray horsetail-like inclusions in the greenish gray region (B), and red platelet inclusions in the red region (C). Photomicrographs by Huizhen Huang; fields of view 1.35 mm, 0.6 mm, and 0.71 mm.
A multi-colored quartz slice was purchased and researched. The Fourier-transform infrared (FTIR) transmission spectra—with weak peaks at 3584 and 2331 cm–1, medium strong peaks at 2924, 2850, 2671, 2597, 2498, and 2136 cm–1, and strong peaks at 3454 and 2242 cm–1—indicate that this is a natural quartz (figure 4).

Figure 4. Fourier-transform infrared (FTIR) transmittance spectrum of the imaged quartz sample. A slice of the tested multi-colored quartz is shown in the inset.

Figure 5. Raman spectra of representative solid inclusions are shown along with the Raman reference spectra from the RRUFF database. Left: The purple zone contained a substantial amount of golden “broom-like” inclusions that matched with goethite. Right: The red platelet inclusions produced a Raman spectrum corresponding to hematite. The black numbers in this figure indicate the Raman peaks of the inclusion, and the gray numbers indicate the peaks of the quartz.
Raman analysis identified the typical inclusions in the purple zones, with peaks at 246, 300, 387, 415, 550, and 685 cm–1 as goethite. The red platelet inclusions with peaks at 225, 245, 293, 411, 499, 611, and 1321 cm–1 are hematite (figure 5). The greenish gray horsetail-like inclusions could not be identified by Raman spectroscopy, so we carried out electron probe microanalysis (EPMA). The chemical analysis of these inclusions are mainly iron (45.49–46.51 wt.%) and sulfur (51.34–51.87 wt.%), indicating that they are FeS2 inclusions.
Considering the multi-colored zones and different oriented inclusions, this quartz likely formed and crystallized in multiple stages. However, the origin of this special pattern still remains unclear and is worth further research. @topic:1


Publish Year: 2017 Title: Elements in Synthetic Overgrowth on Flux-Heated Ruby and Beryllium-Diffused Sapphire Abstract: Figure 1. Synthetic overgrowth on the surface of a heated Burmese ruby. Photo by Yusuke Katsurada; field of view 1.50 mm.

Heat treatment of rubies and sapphires at high temperatures sometimes leaves redeposition caused by the partial dissolution of the corundum in the crucible; this is referred to as synthetic overgrowth (Fall 2002 GNI, pp. 255–256). GIA’s Tokyo laboratory recently had the opportunity to test a red oval mixed cut weighing 2.00 ct and an orange round mixed cut weighing 0.89 ct, both of which showed signs of synthetic overgrowth after testing.

Standard gemological testing and advanced testing including chemical analyses revealed that the red oval was a heated ruby of Burmese origin with moderate flux residues in fissures. The orange round was identified as a beryllium-diffused sapphire. Both stones had synthetic overgrowth around the girdles and/or cavities (figures 1 and 2) that could be confirmed by different reactions under cross-polarized light. We tested the overgrowths with laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) with calibration using NIST 612 and 610 standards.

Figure 2. Synthetic overgrowth on an orange beryllium-diffused sapphire. Photo by
Yusuke Katsurada; field of view 1.60 mm.
The chemical compositions of these synthetic overgrowths were different from those of corundum; they also varied between the samples. Sodium (9980 ppmw), calcium (40,100 ppmw), magnesium (84,400 ppmw), and silicon (23,400 ppmw) were extremely high in the overgrowth on the flux-heated ruby; beryllium (36,650 ppmw) was extremely high and silicon (909 ppmw) very high in the overgrowth on the beryllium-diffused sapphire (table 1). Boron was detected only in the overgrowth on ruby (59 ppmw). Aluminum was not quantified since it was used as an internal standard. However, the high aluminum signal indicated that the overgrowth contained corundum and/or alumina-related material.

TABLE 1. Elements in heated ruby and Be-diffused sapphire and their synthetic overgrowths detected by LA-ICP-MS (avg. concentration in ppmwa).

Heated ruby
Be-diffused sapphire

Element
Stone
Overgrowth
Stone
Overgrowth

Be
bdlb
5.00
8.86
36,650c

B
bdl
59.0
bdl
bdl

Na
bdl
bdl
10.6
10.6

Mg
10.5
61.1
328
328

Si
bdl
bdl
909
909

K
bdl
1790
bdl
bdl

Ca
bdl
40,100
bdl
bdl

Ni
bdl
104
0.42
6.20

Cu
1.71
50.1
bdl
8.34

Zn
bdl
64.0
bdl
12.7

Zr
0.04
27.6
bdl
296

Pb
bdl
93.7
bdl
0.15

a All detection limits are below 4 ppmw except for Si (heated ruby: 113.5 for stone, 104.1 for overgrowth; Be-diffused sapphire: 93.3 for stone, 80.0 for overgrowth) and Ca (heated ruby: 16.95 for stone, 15.79 for overgrowth; Be-diffused sapphire: 16.95 for stone, 15.79 for overgrowth).
b bdl: below detection limit
c These values were linearly extrapolated with pulse-analog linear dynamic range measurement of the instrument.

Flux is used for artificial heat treatment of rubies, and there are many types of fluxes such as oxides, borates, silicates, molybdates, and fluorides, as well as various combinations of materials (J.L. Emmett, “Fluxes and the heat treatment of ruby and sapphire,” Fall 1999 G&G, pp. 90–92). During flux-assisted heat treatment with or without diffusion, material from the surface of the corundum as well as the alumina crucible and inclusions will dissolve to some degree into the molten flux. On cooling, the flux becomes supersaturated in alumina and crystallizes out onto the nearest convenient surface, often on the stones themselves (J.L. Emmett et al., “Beryllium diffusion of ruby and sapphire,” Summer 2003 G&G, pp. 84–135). Uncommon elements for corundum such as sodium, calcium, and silicon obtained from the overgrowth on heated ruby in high concentration indicate that the overgrowth was mainly derived from fluxes. These elements are comparatively insignificant for the overgrowth on beryllium-diffused sapphire. On the contrary, extraordinarily high beryllium in the overgrowth on Be-diffused sapphire indicates deposition of this additional element in the treatment. Other elements, such as magnesium and zirconium (detected at moderate to high levels), and metals such as nickel, copper, zinc, and lead (detected from both overgrowths at lower levels) may be from the inclusions or the flux.

LA-ICP-MS results (table 1) also indicate that the ruby could be misidentified as Be-diffused since the overgrowth contains a certain amount of beryllium, a possible by-product of the furnace. It is important for gemologists to check other elements such as magnesium, silicon, and calcium in order to confirm that LA-ICP-MS was performed on the overgrowth. @topic:3


Publish Year: 2021 Title: James Shigley Receives Robert M. Shipley Award Abstract: Dr. James Shigley is the 2021 recipient of the American Gem Society’s Shipley Award. Photo by Kevin Schumacher.

Dr. James E. Shigley, GIA’s distinguished research fellow, has received the American Gem Society’s Robert M. Shipley Award for his significant contribution to the science of gemology. The prestigious award was announced at the AGS Conclave in Dallas on September 13. Dr. Shigley was unable to attend the ceremony but was honored at GIA’s Carlsbad campus by president Susan Jacques, research colleagues, and family, where he was presented with a plaque and pin acknowledging his decades of commitment to gem research.
During his almost 40-year career with the Institute, Shigley has authored or coauthored more than 85 Gems & Gemology articles, edited the G&G In Review book series, and been the face of GIA’s research mission, lecturing extensively on gems and gem identification. He is also the recipient of the 2017 AGS Lifetime Achievement Award. @topic:11


Publish Year: 1994 Title: Synthetic Forsterite and Synthetic Peridot Abstract: Large crystals of chromium-containing synthetic forsterite are being commercially manufactured for use as a laser material. Considerable color variation is possible, and some of this material resembles peridot, with which it could be confused. Synthetic peridot has been grown, but only experimentally. This material closely resembles natural peridot and might be difficult to distinguish if it were to appear in the gem market. @topic:8


Publish Year: 1983 Title: Peridot from Tanzania Abstract: Peridot from a new locality, Tanzania, is described and compared with 13 other peridots from various localities in terms of color and chemical composition. The Tanzanian specimen is lower in iron content than all but the Norwegian peridots and is very similar to material from Zabargad, Egypt. A gem-quality enstatite that came from the same area in East Africa and with which Tanzanian peridot has been confused is also described. @topic:2


Publish Year: 1982 Title: The Jade Enigma Abstract: Jade is one of the most misunderstood gemstones. It is actually two separate materials: jadeite and nephrite. Together, these materials have more simulants than most other gems. Thus, it is important to know the various simulants, and to understand how to separate them from jade. This article examines the key identifying properties of green jade (jadeite and nephrite) and contrasts them with the properties of the 10 most common green jade simulants. Simple visual techniques are emphasized as well as the appropriate gemological tests. @topic:9


Publish Year: 2015 Title: Blue Chalcedony Partially Filled with Epoxy Resin Abstract: Figure 1. The eye-catching carving weighing 18.43 ct and measuring 31.7 × 15.7 × 7.6 mm, submitted for identification as blue chalcedony. Photo by Larry Tai-An Lai.

Blue chalcedony is one of Taiwan’s most famous stones; there, high-quality blue chalcedony is sometimes prized as much as jadeite jade. Compared with production from sources such as the United States, Indonesia, Peru, Mexico, and Chile, chalcedony from DuLan Mountain in Taitung, in southeast Taiwan, reveals fine texture and a saturated blue color. Locals and tourists collect the stone as it symbolizes the national spirit, and its value seems to rise year after year.

Local merchants often sell blue chalcedony under the name “Taiwanese blue sapphire,” leading to confusion among consumers who believe they are purchasing sapphire. Imitations and treatments are also of concern in the market, with blue opal the most likely imitation to confuse would-be purchasers at first glance. Dyed quartzite and dyed chalcedony also rank among the more common imitations encountered.

Figure 2. Raman peaks at 120, 196, 461, and 499 cm–1 matched the pattern expected for blue chalcedony.

Figure 3. The blue chalcedony’s Raman peaks at 638, 821, 1111, and 1607 cm–1 matched those expected for epoxy resin.
The Lai Tai-An Gem Lab in Taipei recently received for identification an 18.43 ct carving measuring 31.7 × 15.7 × 7.6 mm (figure 1). The client claimed the uneven blue and brown translucent item was blue chalcedony. The spot RI of 1.53, SG of 2.55, and FTIR results were consistent with published values for blue chalcedony. Raman peaks at 120, 196, 461, and 499 cm–1 (figure 2) confirmed the identity but displayed additional peaks not related to blue chalcedony (figure 3). Examination with a gemological microscope at 40× magnification, which was increased in increments up to 60×, revealed a structure consistent with blue chalcedony but also explained the source of the suspicious Raman peaks: numerous clear bubbles of different sizes at the border of the blue- and brown-colored areas, as seen in figures 4 and 5. The evidence pointed to an epoxy resin as the foreign material; a moderate blue reaction under long-wave UV seemed to confirm a partially filled portion on the carving. Additional Raman analysis on the area in question showed peaks at 638, 821, 1111, and 1607 cm–1 (again, see figure 3), as expected for epoxy resin.

Figure 4. Numerous transparent bubbles of different sizes were visible within a treated
portion of the blue chalcedony carving at the border of the blue and brown areas.
Photo by Larry Tai-An Lai; inset magnified 60×.

Figure 5. The epoxy resin area as seen through a gemological microscope. Photo by Larry Tai-An Lai; magnified 40×.
In our experience, blue chalcedony is seldom treated, and such treatment is usually applied to repair or conceal cavities or fractures. Even when a filling is only partial, as in this example, traders should disclose any treatments to their clients. @topic:1


Publish Year: 2024 Title: Iridescent Healed Fissures in Epidote Abstract: Iridescent healed fissures observed in a 4.18 ct faceted epidote. Photomicrograph by Tinh Xuan Nguyen; field of view 2.5 mm.
The author recently examined a 4.18 ct yellowish brown cushion-cut epidote. Under fiber-optic illumination, the stone revealed iridescent healed fissures (see above). Healed fissures are not uncommon in various gemstones. They are believed to result from a secondary fluid that facilitated the healing process of previously surface-reaching fractures. In the case of this epidote, the healed fissures resulted in a striking feature revealed when illuminated under the microscope. @topic:3


Publish Year: 2022 Title: Fracture-Filled Emerald with Mysterious Filler Patterns Abstract: Emerald filler with labyrinth- and convolution-like pattern. Photomicrographs by Ungkhana Atikarnsakul; fields of view 2.0 mm (left) and 2.7 mm (right).
Emeralds are known to have natural cracks or fractures. The filling of surface-reaching fractures with various oils and resins is the most common practice to minimize fractures to improve an emerald’s appearance. The author recently examined a 3.04 ct emerald that revealed a mysterious filler pattern along the fractures, resembling a labyrinth and convolution (see above). Fracture filling can be identified using various methods. In this case, it displayed a chalky fluorescence under long-wave ultraviolet flashlight and was also detected with simple microscopic observation and fiber-optic lighting. The internal graining, irregular two-phase inclusions, and long needles within this stone indicated a natural origin. This was a unique and visually interesting pattern in the fracture filling material of an emerald. @topic:3


Publish Year: - Title: Artistry of a Peruvian Master Gem Carver Abstract: Play

Interview with Luis Quispe, Neoart Peru

Luis Quispe, a talented young gemstone carver from Lima, Peru, showcases his eye-popping work in this video. He is the second generation in a 30-year-old fine gem-carving family business that emphasizes the creation of original contemporary styles. His love of design, and of the raw gem materials he shapes, shines through in his every word and gesture.

Among the many gorgeous examples Quispe demonstrates is a “Marine Life” chess set designed by his sister Silvia. One set of chessmen (actually swordfish, carp, seahorses, marlin, and sea turtles) is carved from Tanzanian ruby and Peruvian pink opal, and the other from Afghani lapis lazuli and Brazilian rock crystal. Luis’ own favorite pieces comprise a set of skulls, each with a distinct personality, that he created out of gem materials from around the world: Canadian jade, Angolan aquamarine, Russian obsidian, Brazilian amethyst, and many more.

When asked how long it takes him to come up with the design for a carving, he says that he has to wait until the stones speak to him. He may look at a piece of raw material every day for a year before the stone reveals the perfect design to him; other times it may take only a day. Luis Quispe clearly knows how to speak the language of gemstone carving. @topic:6


Publish Year: - Title: Canadian Mining Industry: Taking a Step Up with Range of Operations Abstract: The expansion of various mining projects in Canada’s North (Northwest Territories, Yukon, and Nunavut) is set to lead the country in economic growth over the next two years. Spinoff activity that accompanies mine-related prosperity is also expected to increase based on pending mines in the assessment phases or preproduction stages, thus further boosting employment and local economic development. The projections see productions in these areas lasting well into the coming decades. Environmental groups and local residents are also interested in the impact on the Canadian North ecosystem as well as the long-term effects on the towns and industry when the boom is over.

Abstracted by Michele Kelley @topic:9


Publish Year: 2016 Title: Purple Pyrope-Almandine Garnet From Mozambique Abstract: Figure 1. These purple pyrope-almandine garnets are from Manica Province of Mozambique. The rough specimens weigh (clockwise from left) 1.49, 1.14, 1.11, and 1.77 ct, while the faceted stone in the center weighs 2.34 ct. Photo by Lhapsin Nillapat.

	In early 2016, attractive purple garnets from East Africa started to appear in the Bangkok market (T. Sripoonjan and T. Leelawatanasuk, “Preliminary investigation of purple garnet from a new deposit in Mozambique,” GIT Gemstone Update, 2016, pp. 1−6). Author VP purchased 17 samples (figure 1) at the Bangkok Gem Fair and inquired about their origin. Mark Saul of Swala Gem Traders (Arusha, Tanzania) informed him that the source was a very unstable area of Manica Province in central Mozambique. Ameen Ikram, a gem merchant from Sri Lanka, confirmed this after managing to visit the mining site in June 2016. The deposit is located about 60 km northeast of Chimoio, near Gorongosa National Park. The area is under the control of the Mozambican National Resistance (RENAMO), an armed rebel group.

	The stones exhibited a vitreous luster. Standard gemological testing yielded an isotropic RI reading of 1.767 ± 0.003 and an SG value of 3.87 ± 0.02. An isotropic reaction with anomalous double refraction (ADR) was observed through the polariscope. The samples were inert when exposed to both long-wave and short-wave UV radiation. Examination with a gemological microscope revealed several internal features (figure 2), including individual and clustered zircon crystals, zircons with stress halos, black platelets of graphite, groups of colorless quartz crystals, thin films, needles, tubes, and iron stains in tubes. Raman spectroscopy was used to identify the mineral inclusions.

	Figure 2. Magnification of the pyrope-almandine garnets revealed several internal features: (A) zircon inclusions with stress halos and needles, field of view 1.4 mm; (B) thin films, field of view 3.5 mm; (C) groups of colorless quartz, field of view 1.8 mm; and (D) a platelet of black graphite, field of view 1.8 mm. Photomicrographs by Victoria Raynaud.

	Advanced analytical techniques, including UV-Vis-NIR and Fourier-transform infrared (FTIR) spectroscopy and laser ablation−inductively coupled plasma−mass spectrometry (LA-ICP-MS), were used to collect additional information. The UV-Vis-NIR spectrum (figure 3, left) indicated electronic transitions of specific Fe and very weak Mn transition metal ions, as described in the literature (K. Krambrock et al., “Purplish-red almandine garnets with alexandrite-like effect: Causes of colors and color-enhancing treatments,” Physics and Chemistry of Minerals, Vol. 40, No. 7, 2013, pp. 555−562). All of the samples showed an iron spectrum including Fe2+ and Fe3+, and a weak absorption peak at 408 nm was assigned to Mn2+. The FTIR spectrum (figure 3, right) showed Fe2+ peaks at 4450 and 5820 cm−1 (R.G. Burns, Mineralogical Applications of Crystal Field Theory, Vol. 5, Cambridge University Press, Cambridge, UK, 1993, pp. 155−158), hydroxyl group features at around 3500−3600 cm−1 (G.R. Rossman et al., “Quantitative analysis of trace OH in garnet and pyroxenes,” American Mineralogist, Vol. 80, No. 5−6, 1995, pp. 465−474), and CO2 peaks at 2340−2360 cm−1. A minor FTIR peak at 2627 cm−1 might have resulted from the numerous inclusions in the samples. LA-ICP-MS analysis (table 1) revealed major amounts of Si, Al, Fe, and Mg, as well as minor amounts of Ca and Mn. Vanadium was also detected in very low concentrations, while titanium and chromium were below the detection limits. The LA-ICP-MS data confirmed the material’s identification as pyrope-almandine garnet with the following chemical components: 48.8−59.5% pyrope, 37.9−47.6% almandine, 2.0−3.5% grossular, and 0.5−0.6% spessartine.

TABLE 1. LA-ICP-MS analyses of pyrope-almandine garnets from Mozambique.

				Oxide

				Weight (%) ± SD (n = 5)

				SiO2

				42.34 ± 0.33

				Al2O3

				25.41 ± 0.22

				FeO

				17.93 ± 1.31

				MgO

				13.16 ± 1.19

				CaO

				0.94 ± 0.20

				MnO

				0.22 ± 0.02

				V2O3

				0.002 ± 0.001

				Cr2O3

				bdl

				TiO2

				bdl

					n: number of studied samples
					bdl: below detection limit
					SD: standard deviation

	Figure 3. Left: The purple garnet’s UV-Vis-NIR spectrum shows weak absorption bands attributed to Fe3+ (337, 367, and 424 nm) and Mn2+ (408 nm). The remaining peaks in the visible region (400, 461, 504, 523, 575, 619, and 698 nm) can be assigned to Fe2+. Right: The FTIR spectrum reveals Fe2+ bands at 5820 and 4450 cm–1, hydroxyl group features at 3552 and 3525 cm–1, and CO2 peaks at 2360 and 2341 cm–1. The very small peak at 2627 cm–1 may be caused by the samples’ numerous inclusions.

	The UV-Vis-NIR spectrum explains the purple color of the samples. Since the main absorption bands dominate the green-yellow regions of the visible spectrum, two strong blue and red transmission regions combine to produce an eye-visible purple color. These samples can be classified as pyrope-almandine garnet, commonly referred to as “rhodolite” garnet. @topic:1


Publish Year: 2020 Title: Dyed Chalcedony Imitation of Chrysocolla-in-Chalcedony Abstract: Figure 1. The Raman spectrum of the loose chalcedony compared to that of chrysocolla and blue chalcedony reveals a mineral composition of quartz (463 cm–1) and moganite (501 cm–1) but a lack of chrysocolla inclusions (3619 cm–1).
Chrysocolla-in-chalcedony, also known as gem silica or blue chalcedony in Taiwan, is the most valuable chalcedony variety on the Taiwanese market. The beautiful greenish blue color is derived from micro-inclusions of chrysocolla, which can be identified by observation of a peak at 3619 cm–1 in the Raman spectrum. This peak can be assigned to OH groups in chrysocolla. Therefore, the color origin for this material is fundamentally rooted in the presence of Cu2+ ions in the structure of the chrysocolla inclusions. In the past few years, a large number of dyed chalcedony imitations have appeared in Taiwan’s market. The blue color of chalcedony dyed by copper salts, and that of natural specimens containing chrysocolla, is caused by Cu2+ ions.
Recently, a parcel of loose chalcedonies was sent to the Taiwan Union Lab of Gem Research (TULAB) for identification. These stones were submitted as natural blue chalcedony, but Raman spectroscopy later confirmed them as chalcedony without the characteristic peaks of chrysocolla (figure 1).

Figure 2. A blue mantle zoning on the cross section of the loose chalcedony is due to the bath of copper dye. Photo by Shu-Hong Lin.
With the owner’s consent, we cut one cabochon and polished the cross section displaying a blue mantle zoning from surface to center parallel to its profile (figure 2). The sample was analyzed with EDXRF, and concentration mapping on the cross section confirmed that copper was concentrated on the surface and decreased toward the interior, which is strong evidence for dyeing with copper salts (figure 3).

Figure 3. The concentration mapping for copper on the cross section of dyed chalcedony, which shows higher copper concentration in the periphery and lower in the interior; the different colors on the right represent the degree of relative concentration for copper from high to low.
Twenty pieces of chalcedony dyed with copper salts were further analyzed with EDXRF and compared to results from twenty pieces of natural blue chalcedony. EDXRF results indicated that the Si/Cu ratio of chalcedony dyed with copper salts was much higher than that of natural blue chalcedony (400–600 and 4–50, respectively). The content of Cu was relatively low in dyed chalcedonies tested.
There are many types of dye used for the color enhancement of chalcedony. Although a series of tests like those used above provide a comprehensive comparison between natural blue chalcedony and the dyed chalcedony analyzed in this research, it requires further verification whether these methods can be applied to other dyed chalcedonies. @topic:1


Publish Year: 2016 Title: Ruby and Sapphire from Muling, China Abstract: Figure 1. Muling, the site of an emerging corundum deposit, is located in northeastern China.

	Only a few Chinese sources produce gem-quality corundum, such as Changle, in Shandong province, but sapphires from that location are not considered top quality in the trade because of their dark hues. An emerging deposit in Muling, in northeast Heilongjiang province (figure 1), produces gem-quality corundum comparable to some world-renowned sources. The main deposits are seated in mountain valleys about 70 km from the town center. Corundum was known in Muling as early as 1985; after preliminary exploration, further activity virtually stopped because of technical and logistical limitations. As a result, production has been very limited, and very little information was published about rubies and sapphires from Muling until 1995 (J.X. Sun, “Basalt related to ruby and sapphire in eastern Heilongjiang and reconstruction of paleovolcanic mechanism,” Acta Petrologica et Mineralogica, Vol. 14, No. 2, 1995, pp. 126–132).

	According to Aijun Yi, director of mineral resource administration in Muling, the region has produced large amounts of gem-quality eluvial materials since 1994, including corundum, brownish red zircon, garnet, and spinel (T. Chen et al., “Brownish red zircon from Muling, China,” Spring 2011 G&G, pp. 36–41). As colored stones became more popular in the Chinese gem markets, interest in ruby and sapphire from Muling grew accordingly.

	We acquired a parcel of rubies and sapphires from local miners. The stones ranged from 0.8 to 15.2 ct (figure 2). Most exhibited well-formed tabular hexagonal crystals, though some broken sapphires had a tumbled appearance. The sapphires were pink, yellow, violetish blue, greenish blue, light blue, and deep blue; there were also near-colorless specimens. Most of the rubies and pink sapphires had a purplish component. Samples other than the deep blue material showed high transparency. Rubies and pink sapphires exhibited medium red fluorescence under long-wave (356 nm) UV light and a weak reaction under short-wave (245 nm) UV. Other varieties of sapphire had no reaction under long- or short-wave UV.

Figure 2. Ruby and sapphire rough from Muling exhibited well-formed tabular hexagonal crystal forms; some sapphires showed a tumbled appearance in broken pieces. Photo by Yimiao Liu.

	The samples generally showed abraded features and unhealed fissures, but some were predominantly clean under the loupe and large enough to be faceted. Fourteen stones were fabricated as parallel polished windows for microscopic examination. Several interesting internal features were visible under the microscope. The inclusions, which mainly appeared as rounded single crystals or multiphase syngenetic clusters, were in micron sizes (50–200 µm) and were identified by Raman as feldspar and sillimanite. The latter mineral only occurred as component mineral crystals in a multiphase inclusion. Most rubies hosted whitish needles forming three-dimensional skeleton networks that might be the result of diaspore exsolution (figure 3). Further microscopic observations under polarized light showed characteristic lamellar twining structures in every sample.

Figure 3. A detailed structure of whitish needles forming a three-dimensional skeleton network in a ruby sample. Photo by Yimiao Liu.

	Trace element analysis by LA-ICP-MS showed a Cr content of 173–636 ppma in the pink-red series, accompanied by a significant level of Fe (1650–2510 ppma) and a noticeable level of Ti (36–70 ppma) to add a blue component through Fe-Ti intervalence charge transfer. This explained why Muling rubies and pink sapphires always had a purplish hue. Mg content was about 46–79 ppma, while Ga (13–17 ppma) fell into the expected range for natural corundum.

	Yellow sapphires showed the highest Fe content (4480–4800 ppma); this contributed to their saturated yellow coloration. Iron content was much lower in blue sapphires, along with an appreciable amount of titanium (80–500 ppma) as a blue chromophore. Based on color distribution and transparency, blue sapphires could be grouped as either light blue or deep blue. Most of the light blue sapphires had very high transparency and even color distribution, while deep blue sapphires were less transparent, with hexagonal dark blue color zoning. Among all blue samples, Mg content ranged from 10 to 80 ppma and did not show clear correlation to color, while Ga content (10 to 100 ppma) was noticeably higher than in rubies and pink sapphires.

	At Muling, most rubies and sapphires are found by casual surface digging. Gem-quality corundum usually occurs in eluvial deposits derived from weathered Cenozoic alkali basalts. Unlike other igneous-related deposits known for dark blue sapphires and very limited red material, such as Australia’s Anakie and New England fields (T. Coldham, “Sapphires from Australia,” Fall 1985 G&G, pp. 130–146) and Shandong, China (C. Simonet. et al., “A classification of gem corundum deposits aimed towards gem exploration,” Ore Geology Reviews, Vol. 34, 2008, pp. 127–133), in Muling ruby production was larger than that of sapphire; over 60% of pink sapphires and rubies were high-quality materials.

	In some ways, some Muling rubies have competitive advantages over Mozambique specimens. Their high color saturations and particular internal features (whitish needles forming three-dimensional skeleton networks) resembled those of rubies from Mozambique and might cause confusion in gem markets. On the other hand, blue sapphires from Muling have a pure blue color with no gray component. The variety of colors and the amount of fancy sapphires found in Muling are quite different from sapphires from other classic igneous deposits (see again Simonet et al., 2008).

	At present, the precise location of the Muling gem deposit source rocks has not been confirmed. According to previous geological studies, the area is localized in the northern terminal of the branch of the Tanlu fault (Z. L. Qiu et al., “Trace element and hafnium isotopes of Cenozoic basalt-related zircon megacrysts at Muling, Heilongjiang Province, northeast China,” Acta Petrologica Sinica, Vol. 23, No. 2, 2007, pp. 481–492). The lava in this region can be divided into six volcanic eruption cycles; Muling has experienced three such cycles (Sun et al., 2005).

	Based on mining and geological information and our analysis of Muling rubies and sapphires, we inferred that this material might have originated as xenocrysts from an earlier volcanic eruption and undergone subsequent high-pressure geological processes. These are likely non-classic alkali basalt deposits. Large corundum deposits exist from eastern China to Primorye in far eastern Russia (I. Graham et al., “Advances in our understanding of the gem corundum deposits of the West Pacific continental margins intraplate basaltic fields,” Ore Geology Reviews, Vol. 34, pp. 200–215), but exact locations have not been confirmed.

	Although Muling’s corundum deposit have yet to be mined commercially, the existing production has drawn the attention of Chinese gemologists and gem dealers. The production may rival that from other high-quality deposits, and this source holds great promise for the future. @topic:2


Publish Year: - Title: Robert M. Shipley Sr. (1887–1978) Abstract: During the depths of the Depression, a middle-aged man with little more than ambition and charisma revolutionized the gem and jewelry industry. Robert M. Shipley established the Gemological Institute of America in 1931 as an education and research facility dedicated to the study of gems. From humble beginnings in his Los Angeles apartment, GIA would go on to become a global leader in gemology.

Shipley began his career as a retail jeweler in Wichita, Kansas. Although he cultivated the image of a gem expert, several embarrassing episodes revealed his lack of training. Divorce and the failure of his business during the mid-1920s sent him in search of a new life in Paris studying art. There he met his second wife, Beatrice, who introduced him to the right people and got him started as a museum lecturer. At the same time he discovered his love of teaching, Shipley enrolled in gemological correspondence courses offered by Great Britain’s National Association of Goldsmiths.

Inspired by the NAG courses and painfully aware of how little most retail jewelers knew about gems, Shipley returned to the United States with a vision: professionalizing the jewelry trade through education. GIA was the first organization of its kind in the United States. While traveling across the country to promote GIA courses, Shipley also established the Institute’s laboratory and instrument services.

In 1934, Shipley founded the American Gem Society as a professional guild of knowledgeable jewelers. That same year he established Gems & Gemology, GIA’s journal of gemological research. Shipley retired in 1952, but his far-reaching vision would influence future generations of gem and jewelry tradespeople. @topic:6


Publish Year: 2021 Title: Yellow Fluid Inclusions in Transparent Sodalite Abstract: Figure 1. This 7.17 ct colorless sodalite was remarkably transparent and contained interesting fluid inclusions. Photo by Sean-Andrew Z. Pyle.

The authors recently examined a 7.17 ct transparent, near-colorless sodalite submitted for identification service (figure 1). Sodalite is typically encountered as a semitransparent to opaque, violetish blue stone with white calcite veining resembling lapis lazuli.
Hackmanite is the sulfur-bearing variety of sodalite exhibiting tenebrescence (D. Kondo and D. Beaton, “Hackmanite/sodalite from Myanmar and Afghanistan,” Spring 2009 G&G, pp. 38–43). Tenebrescent minerals reversibly change color when exposed to UV light—from light purple to saturated purple, in the case of hackmanite. While this stone showed the strong orange fluorescence reportedly found in hackmanite, no change in color was observed. This was perhaps due to the short exposure time during testing.

Figure 2. These greenish yellow fluid inclusions were identified as hydrogen sulfide in solution. The gas bubble was matched to hydrogen sulfide gas. Photomicrograph by Tyler E. Smith: field of view 1.99 mm.
Microscopic observation revealed greenish yellow two-phase fluid inclusions reminiscent of petroleum in quartz (figure 2). Unlike petroleum in quartz, the fluid inclusions were inert to long-wave UV light. Raman spectra of the gas bubble and surrounding liquid were matched to gaseous hydrogen sulfide and hydrogen sulfide in solution, respectively. Methane-related peaks were also present in the liquid phase. These sulfur-rich fluid inclusions provided interesting geological evidence of the stone’s formation, making this rare sodalite even more exceptional. @topic:1


Publish Year: 2015 Title: Unusual Combination of Inclusions in Synthetic Star Sapphire Abstract: Figure 1. This 8.975 ct specimen was identified as synthetic star sapphire. Photo by Pragati Verma.

Recently, an 8.975 ct blue oval cabochon exhibiting asterism (figure 1) was submitted to the Indian Gemological Institute – Gem Testing Laboratory in Delhi for identification. Standard gemological testing revealed a spot RI of 1.76 and hydrostatic SG of 4.00. These properties were consistent with sapphire.

Figure 2. Three-directional needles intersecting at 60°/120° angles. Also notice the coarse
hexagonal boundary created by the gas bubbles surrounding the three-directional needles.
Photomicrograph by Meenakshi Chauhan; field of view 11.30 mm.
Microscopic examination at 25× magnification showed three-directional “needles” intersecting at 60°/120° angles (figure 2). Under 60× magnification, the three-directional needles appeared as a series of dots. The expected solid rutile needles were not resolved at the magnification used. These three-directional needles were further surrounded by a coarse hexagonal boundary (again, see figure 2) made up of gas bubbles (figure 3, left). The presence of the hexagonal boundary initially led to an impression of natural origin, but the presence of gas bubbles and chalky blue fluorescence under SWUV confirmed a synthetic origin. These three-directional needles (series of dots intersecting at 60°/120° angles) with possibly unresolved rutile needles are responsible for the six-rayed asterism. When the stone was checked in the DiamondView, it showed a dark blue ring around the gas bubbles (figure 3, right). This was the first time this author had seen such a reaction to gas bubbles in a synthetic material in the DiamondView.

Figure 3. Left: Gas bubbles appearing as whitish dots under 50× magnification. Right: DiamondView imaging of the gas bubbles. Notice the dark blue areas visible around the gas bubbles, which were inert to UV. This may indicate compositional variation where the whitish and dark areas are visible in the left-hand image. Photomicrograph and DiamondView image by Pragati Verma.
The three-directional intersecting needles that give rise to asterism in synthetic sapphire are a by-product of the titanium oxide added in the feed material for crystal growth. As mentioned above, the three-directional needles observed here were actually resolved microscopically as a series of dots, and the expected rutile needles were not observed. After growth, the boule was likely reheated, causing the previously disseminated titanium oxide to precipitate out as needles of rutile (R. Webster, Gems: Their Sources, Descriptions and Identification, 5th ed., rev. by P.G. Read, Butterworth-Heinemann, Oxford, UK).

When the sample was viewed in transmitted light, it appeared transparent in the center but translucent from the sides, resembling an eye (figure 4). No gas bubbles were visible in the center of the cabochon, but there were increasingly higher concentrations of gas bubbles toward the edges. Under SWUV, this material showed chalky blue fluorescence confined to the central transparent part. Such hexagonal patterns were previously reported in synthetic sapphire in G&G (Summer 2007 GNI, pp. 177–178). While observing any stone, one must not consider a single inclusion or characteristic, such as the hexagonal boundary observed here, as an indicator of natural or synthetic origin. There must be a thorough examination of all inclusions and properties (in this case, gas bubbles and chalky blue fluorescence under SWUV) to conclude the origin of a material.

Figure 4. Under fiber-optic light, the material showed an eye-like pattern, with a pink and transparent center and blue and translucent sides. Also notice the hexagonal boundary made from the gas bubbles.  Photomicrograph by Pragati Verma; field of view 22.94 mm. @topic:3


Publish Year: 2018 Title: A Rare Ruby from Montana Abstract: Figure 1. Inclusions in the 1.70 ct ruby from Montana. Left: Close-up of a glassy melt inclusion with an associated thin film showing geometric patterns; field of view 1.76 mm. Right: A melt inclusion with an iridescent thin film, partial hexagonal zone of particles, and short needles; field of view 3.81 mm. Photomicrographs by Claire Malaquias.
The Carlsbad laboratory recently received a 1.70 ct purplish red octagonal modified brilliant-cut ruby measuring 6.28 × 6.25 × 4.56 mm for an identification and origin report. Standard gemological testing gave a chromium spectrum indicating ruby and a hydrostatic specific gravity (SG) of 4.00. The stone displayed a weak red fluorescence in long-wave UV and no fluorescence under short-wave UV.
Microscopic examination showed an interesting combination of inclusions (figure 1). There were several glassy melt inclusions and small crystals with associated reflective thin films. The thin films often displayed hexagonal geometric patterns conforming to the crystallographic orientation of the host ruby. These resembled the patterns commonly seen in rubies from Thailand and Cambodia and have also been documented in Montana corundum (Fall 2015 Micro-World, pp. 329–330). A partial hexagonal zone of particles and more loosely spaced unaltered exsolved rutile needles was also present, a feature that would be very unusual in Thai/Cambodian rubies. A large intact colorless crystal as well as smaller white crystals were located deep within the stone, so we were unable to conclusively identify them with Raman spectroscopy. This inclusion scene is consistent with unheated corundum from Montana.

Figure 2. The 1.70 ct Montana ruby alongside rough pink to purple corundum samples from the GIA reference collection. These reference samples, collected from Montana’s Eldorado Bar along the Missouri River and Wildcat Gulch, part of the Rock Creek deposit, were used to help determine the country of origin. Photo by Robison McMurtry.
Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) was used to determine the stone’s trace-element chemistry, and the results were compared to corundum samples from GIA’s colored stone reference collection. Trace element measurements indicated ranges of 15.1–17.2 ppma Mg, 14.7–16.9 ppma Ti, 3.67–3.87 ppma V, 359–406 ppma Cr, 1500–1580 ppma Fe, and 14.6–14.7 ppma Ga. The chemistry matched well with reference stones GIA has collected from Montana’s secondary deposits (figure 2) but not our Thai/Cambodian ruby reference samples. In particular, Thai/Cambodian rubies tend to have higher Mg (often above 100 ppma), while this stone had much lower Mg levels.
Montana’s secondary deposits produce sapphires in a wide range of mostly pastel colors. Pink corundum tends to be rarer than blue or green, and those that possess the depth of color to be called ruby are quite rare, particularly without any treatments. The color, combined with the large size, makes the 1.70 ct ruby from Montana an exceptional specimen—this is only the second such report issued by the lab to date. With a combination of microscopic observation, advanced testing methods, and GIA’s reference collection, we were able to confirm the country of origin. @topic:3