Title: UV-Reactive Opal Abstract: Figure 1. Note the milky white color of these two polished opals before exposure to long-wave ultraviolet light. Photo by Don Mengason.

              A pair of milky white polished opals, weighing 2.66 and 2.48 ct, were recently examined at the Carlsbad laboratory (figure 1). Spot RI readings of 1.44 and 1.43, respectively, were consistent with opal. The stoneswere placed under long-wave ultraviolet light (LWUV) as part of the routine testing.

Upon removal from the UV light source, it was apparent that the opals’ color had changed to a bright orangy red. Further gemological testing confirmed that the specimens had been impregnated with an unknown photochromic substance that changed color when exposed to UV light. The color change (figure 2) occurred after approximately one minute of exposure. The orangy red color faded completely about five minutes after removal from the UV source. Furthermore, when the specimens were placed near a window, sunlight provided enough UV radiation to fully induce the orangy red color. This reversible and repeatable effect, known as tenebrescence, is occasionally seen in natural materials, most notably hackmanite. Exposure to the light of an incandescent bulb faded the color faster, which is another property of tenebrescence. Exposure to short-wave UV did not produce any visible effect on the color.

	Figure 2. The same two opals are shown after exposure to long-wave UV. Photo by Don Mengason.
The fact that hydrophane opal allows foreign substances to be introduced has already been established (N. Renfro and S. McClure, “Dyed purple hydrophane opal,” Winter 2011 G&G, pp. 260–270). This was in the context of dyeing with a substance that altered the appearance of the bodycolor, but did not change color in the presence of UV light. Impregnating opal with a UV-reactive chemical to make the opal appear to be tenebrescent has not been previously documented. Whether the substance used to impregnate the opals affected the original color or transparency is not known, nor is the stability of the treatment. Source: GIA @topic:11


Title: Unique Tourmaline Necklace Abstract: A unique parti-color Brazilian tourmaline necklace with a total weight of 961 carats. Photo by Duncan Pay/GIA, courtesy of Atlas Gemstones, Inc.

              At the AGTA show, Anna Jankowiak (Atlas Gemstones Inc., Toronto) showed us a unique 961 ct parti-color tourmaline necklace and clasp (figure 1). This piece, which Ms. Jankowiak said she purchased in India, was reportedly cut from a single large, slender Brazilian tourmaline crystal reportedly mined within the last three years. The cutter tried to salvage as much of the material as possible by slicing down the crystal’s length. This produced large flattened sections with rounded edges that showed alternating green and pink color zoning down their lengths. The zoning was strong, neat, and “tight.” This was in contrast to many of the parti-color tourmaline crystal slices we saw at the show, which were sliced perpendicular to their lengths to show the typical concentric “watermelon” zoning. Source: GIA @topic:10


Title: Spiky Inclusion in Padparadscha Sapphire Abstract: A view through the table of a padparadscha sapphire displayed this jagged suspended crystal, likely a metal sulfide, featuring a rare texture. Photomicrograph by Courtney Robb; field of view 2.90 mm.
A peculiar inclusion with metallic luster (see above) was observed in a 5.31 ct faceted pinkish orange padparadscha sapphire. Though reminiscent of an inclusion previously observed in garnet (Summer 2023 G&G Micro-World, p. 226), this occurrence in sapphire displayed a more irregular and pronounced spiky texture. The combination of nearly pyramidal protrusions and sloped valleys gives this inclusion a fascinating and unique topography. While neither inclusion was conclusively identified, the opacity and dark metallic appearance suggest a metal sulfide. Source: GIA @topic:3


Title: Molybdenite in Topaz Abstract: Figure 1. This 4.71 ct Brazilian colorless topaz hosts a cluster of hexagonal molybdenite crystals. Photo by Kevin Schumacher.

	A photogenic cluster of hexagonal molybdenite crystals (MoS2) was recently discovered in a 4.71 ct transparent colorless hexagonal step-cut topaz (figure 1). The topaz host was identified using traditional gemological testing, and the molybdenite cluster (figure 2) was identified through its metallic luster, morphology, and the presence of molybdenum, which was detected using focused EDXRF analysis.

Figure 2. It was a surprise to discover molybdenite crystal inclusions in topaz. Shadowed lighting reveals iridescence and surface details on the cluster, which measures 2.82 mm in length. Photomicrograph by Nathan Renfro.

	This gem, which came from Luciana Barbosa of the Gemological Center in Ashville, North Carolina, is from Seridó, Rio Grande do Norte, Brazil. We have never seen this inclusion-host association before, and it is not previously recorded in the literature. This elegant gem is a perfect micromount of molybdenite in a faceted showcase. Source: GIA @topic:2


Title: YAG with Flux-Filled Fingerprints Abstract: Flux-filled fractures displaying geometric shapes and iridescent colors when viewed through crossed polarizers. Photomicrograph by Michaela Stephan; field of view 2.9 mm.
The author recently examined a 3.58 ct yellowish green yttrium aluminum garnet, a manufactured product known in the trade as “YAG,” that contained numerous large flux-filled fractures. The flux material crystallized in the fractures formed interesting geometric shapes that showed birefringent interference colors when viewed between crossed polarizers, reminiscent of stained glass windows (see above). It is possible this YAG was intentionally fractured and filled with flux to more convincingly imitate tsavorite grossular garnet. Although the flux inclusions in this example were quite beautiful, such inclusions are not common in this manufactured gem material. Source: GIA @topic:3


Title: Solution-Generated Pink Color Surrounding Growth Tubes and Cracks in Blue to Blue-Green Copper-Bearing Tourmalines from Mozambique Abstract: Several transparent, faceted, blue to blue-green copper-bearing tourmalines containing growth tubes and cracks surrounded by sleeves of pink color were examined for this report. On the basis of micro-observation, it is theorized that a radioactive solution was the probable cause of the pink color. The presence of the pink zones also supplied visual evidence that the host tourmalines had not been heat treated. Source: GIA @topic:11


Title: Beryl Crystal in Fluorite Abstract: A colorless prismatic beryl crystal within a fluorite specimen from the White Mountains in Inyo County, California. Photomicrograph by Nathan Renfro; field of view 8.60 mm.

Recently, the authors examined a purple fluorite specimen that contained an elongate hexagonal rod-shaped crystal (see above). The crystal host had been collected by Chris Lehmann (Lehmann Minerals, Benton, California) in the Birch Creek area of the White Mountains in Inyo County, California. This area was host to volcanic activity that resulted in granitic dikes cutting across dolomite and other sedimentary rock types. The most abundant minerals found in the area are quartz, calcic oligoclase, microcline, biotite, and muscovite. Smaller amounts of apatite, zircon, tourmaline, magnetite, epidote, purple fluorite, and beryl have also been reported (C.A. Nelson and A.G. Sylvester, “Wall rock decarbonation and forcible emplacement of Birch Creek Pluton, southern White Mountains, California,” Geological Society of America Bulletin, Vol. 82, No. 10, 1971, pp. 2891–2904). While the morphology of the prismatic inclusion hinted at its identity, the hexagonal crystal was conclusively identified as beryl by laser Raman spectrometry. Also present in the fluorite were numerous veils of fluid inclusions and prominent color zoning (again, see above). This exciting discovery was the authors’ first encounter with beryl as an inclusion in fluorite. Source: GIA @topic:2


Title: The 3543 CM-1 Infrared Absorption Band in Natural and Synthetic Amethyst and its Value in Identification Abstract: The proper use and limitations of IR spectroscopy for identifying natural versus synthetic amethyst of various types have been investigated, focusing on the region 3800–3000 cm-1. The presence of absorption bands at approximately 3680, 3664, and 3630 cm-1 unambiguously proves artificial origin, but only for samples grown in near-neutral NH4F solutions. Conversely, there are no unambiguous diagnostic features in the IR spectra of the more commercially significant synthetic amethyst grown in alkaline K2CO3 solutions. Nevertheless, previous investigators have found potential diagnostic value in absorption bands at approximately 3595 and 3543 cm-1. Although the 3595 cm-1 band is not found in the spectra of synthetic amethyst, it also is frequently absent from those of natural amethyst. The 3543 cm-1 band is found in the vast majority of synthetic amethysts grown in alkaline solutions, but this band also is sometimes present in natural amethyst—so it provides only tentative evidence of synthetic origin. Moreover, the 3543 cm-1 band is absent from some varieties of synthetic amethyst. The unambiguous identification of natural versus synthetic amethyst therefore must be based on a combined examination of the IR spectra, internal growth structures (including twinning), and inclusions.

	DATA DEPOSITORY

Table 1: Presence or Absence of the 3543 cm-1 Absorption Band in Synthetic Quartz According to Growth Conditions
	Submitted by Vladimir S. Balitsky
	Summer 2004 Source: GIA @topic:3


Title: Liddicoatite Tourmaline from Anjanabonoina, Madagascar Abstract: Liddicoatite, a calcium-rich lithium tourmaline, was recognized as a separate mineral species in 1977, and named in honor of Richard T. Liddicoat. Most of the remarkable polychrome tourmalines with varied geometric patterns that are characteristic of this species were produced during the 20th century from the Anjanabonoina pegmatite deposit in central Madagascar. To best display its complex color zoning and patterns, the tourmaline is commonly sold as polished slices or carvings. Liddicoatite exhibits physical and optical properties that overlap those of elbaite, so quantitative chemical analysis is required to distinguish these species; both may occur in a single crystal. The most common internal features are color zoning, strain patterns, partially healed fractures, feathers, needle-like tubes, negative crystals, and albite inclusions.

	DATA DEPOSITORY

Table 1: Samples from Madagascar
Table 2: Samples from Localities Other Than Madagascar
	Submitted by Brendan Laurs
	May 17, 2002
	Notes: These tables provide all of the chemical data on liddicoatite-elbaite tourmaline that were obtained for this article. The references cited in the table are listed in the reference list of the original article. Source: GIA @topic:2


Title: Unusual Aquamarine–White Beryl Abstract: Figure 1. A 41.51 ct freeform faceted bicolor beryl. Photo by Marina Boncompagne.
Recently, the author analyzed an interesting 41.51 ct faceted bicolor beryl (figure 1) composed of aquamarine and opaque white beryl. This gem belongs to Brazilian gem dealer Veber Leite and is part of his collection containing several similar specimens. According to Leite, the bicolor beryls were mined in Brumado, a city located in the state of Bahia, Brazil, but their geographic origin could not be confirmed.
Standard gemological testing of both sections revealed a specific gravity of 2.70 and a refractive index of 1.581–1.592. Ultraviolet/visible/near-infrared (UV-Vis-NIR) spectra revealed an absorption band centered at about 810 nm, also present in both sections. In beryl, this band is associated with Fe2+ (D.L. Wood and K. Nassau, “The characterization of beryl and emerald by visible and infrared absorption spectroscopy,” American Mineralogist, Vol. 53, No. 5, 1968, pp. 777–800; Y. Hu and R. Lu, “Color characteristics of blue to yellow beryl from multiple origins,” Spring 2020 G&G, pp. 54–65) and possibly enhanced by neighboring Fe3+ (S. Saeseaw et al., “Geographic origin determination of emerald,” Winter 2019 G&G, pp. 614–646). The blue section exhibited an anisotropic band around 600 nm when viewing an e-ray oriented absorption spectrum, typical of aquamarine (Hu and Lu, 2020). The white color was caused by an isotropic absorption band ranging from 400 to 700 nm with a nearly identical absorption coefficient through all wavelengths.
Although seemingly opaque, when exposed to the polariscope’s intense light source, the white portion allowed the passage of light and showed no extinction under crossed polarizers, suggesting a polycrystalline composition.

Figure 2. The Raman spectra of the blue and white sections in the 41.51 ct bicolor beryl. Spectra are offset vertically for clarity.
Raman spectra were collected at room temperature using a Horiba Scientific LabRAM HR Evolution spectrometer coupled with an Olympus Scientific Solutions BX-41 microscope with a 50× magnification lens. The acquisition time was 120 seconds, grating: 500 nm. For this analysis, a 532 nm excitation laser was selected. Both sections exhibited major peaks around 321, 395, 520, 683, 1011, and 1066 cm–1 (figure 2). Minor peaks were observed at 448, 622, and 1141 cm–1. The spectra were compatible with beryl and, although clarity treatment was not observed, displayed relatively strong absorptions at approximately 1504 and 1567 cm–1 (again, see figure 2) that may suggest the presence of a filling agent (M.L. Johnson et al., “On the identification of various emerald filling substances,” Summer 1999 G&G, pp. 82–107). Additional Raman analysis with a spectral range of 100–3500 cm–1 is required to determine whether the peaks are indeed related to a filling substance.

Figure 3. Left: The aquamarine−white beryl boundary. Right: Beryl channels parallel to aquamarine’s c-axis in the blue portion of the bicolor beryl. Photomicrographs by Marina Boncompagne; field of view 10.00 mm.
Microscopic analysis revealed a well-defined aquamarine–white beryl boundary (figure 3, left). Channels parallel to the c-axis were also observed (figure 3, right).
The author is aware of similar aquamarine−white bicolor beryl from the state of Minas Gerais, but this was the author’s first encounter with such beryl reportedly from Brumado, Bahia. Source: GIA @topic:3


Title: Amber Filled with Epoxy Resin Abstract: Figure 1. Epoxy resin is easily detected in the amber of this rosary. Photo by Nazar Ahmed Ambalathveettil.
Amber prayer beads are very popular in the Gulf countries. Due to this high demand, the Dubai Central Laboratory receives many of them for identification. Recently we noticed that a majority of the amber rosary samples received for identification contain an epoxy resin filling. These fillings are seen in cavities of different sizes but sometimes show up in tiny veins.
The fillings are not always easy to detect without magnification because of the nearly identical luster of both amber and epoxy, but sometimes they are obvious, as shown in figure 1. Occasionally gas bubbles can be observed in epoxy fillings by microscope. Fillings may show a mixed reaction under both long-wave and short-wave UV radiation, and the fluorescence is more intense in long-wave UV. Filled beads can be inert under UV or show weak to strong white or blue fluorescence (figure 2).

Figure 2. When exposed to long-wave UV radiation, the epoxy resin displayed weak to moderate white fluorescence. Photo by Nazar Ahmed Ambalathveettil.

Figure 3. The Raman spectra of the bead and the cavity filling shown here matched with spectra previously reported in G&G for amber and epoxy resin.
To identify the fillings, we observed the rosary under the microscope, marked the suspected areas or spots, and analyzed them by Raman spectroscopy to confirm the presence of fillings. The spectra were compared with those of amber and epoxy reported previously in G&G (figure 3; see Fall 2013 GNI, pp. 181; Summer 2021 GNI, pp. 179–180). Nowadays, having an amber rosary tested by a gemstone laboratory before buying can avoid a costly mistake. Source: GIA @topic:12


Title: New Emerald Locality in Southern California Abstract: Figure 1. A map of California with an inset showing the San Diego area and marking the emerald locality (star).
Located about 60 miles east of San Diego, a new emerald deposit has been discovered in the Julian Mining District (figure 1). This area is known for pegmatite mines and hydrothermal mineral deposits; however, none of those are known to have produced emeralds to date. The emeralds (example shown in figure 2) were all collected by author RE and son Bruce Edley near the surface and are embedded in a biotite schist host rock. Most of the recovered single crystals have a translucent dark green color and inclusions, and they are typically smaller than 2 cm. A few light-colored green beryl crystals have been recovered from a nearby pegmatite. Their formation was likely correlated with metamorphic and hydrothermal processes associated with regional tectonism.

Figure 2. An example of an emerald cluster found in a new deposit in Julian, California. Specimen size is 20 × 10 × 9 mm. Photo by Myke Clarkson.
Samples were analyzed at the Natural History Museum of Los Angeles County and sent to GIA for species confirmation using laser ablation–inductively coupled plasma–mass spectroscopy (LA-ICP-MS). We performed Raman and X-ray fluorescence (XRF) hyperspectral mapping and powder X-ray diffraction (not shown) to determine mineralogy and elemental composition. Raman analysis on a polished pill-shaped gem (figure 3, left) identified beryl and quartz to confirm our observation of the rare combination of emerald and citrine. Raman further identified dolomite and hematite inclusions. XRF element maps (figure 3, right) show silicon (Si), chromium (Cr), magnesium (Mg), iron (Fe), aluminum (Al), and holmium (Ho) content. Of the approximately 425 carats of emeralds that have been recovered, about 5–10% contain macro-citrine inclusions, representing a unique aspect of this deposit.

Figure 3. Left: A 3.16 ct polished pill-shaped emerald, seen in transmitted light, was one of the best examples of emerald with citrine from this locality. Photo by Aaron Celestian. Right: Element maps of the outlined area on the specimen. Brighter areas indicate higher concentrations.
The distribution of trace elements in the pill-shaped emerald indicates a complex series of events. The emerald is cross-cut by a layer of citrine. Half of the gem is enriched in trace holmium (below the citrine), where holmium is inversely correlated with manganese. Chromium-rich areas run perpendicular to the citrine, but align on either side of the citrine, suggesting that the emerald formed as a single crystal. The patterns of holmium and manganese hint toward secondary geochemical processes that may be related to later citrine emplacement, though the origin of these processes is unknown. The unusual mineral associations and elemental distribution demonstrate the geologic complexity of the deposit, and further work is needed to unravel its full history. Source: GIA @topic:2


Title: Une Découverte Exceptionnelle de Béryls Gemmes à Chaves, District de Vila Real, Portugal [An Exceptional Find of Gemmy Beryls at Chaves, District of Vila Real, Portugal] Abstract: The numerous pegmatites in northern Portugal are known as sources of fine mineral specimens for collectors. A passionate rockhounding couple describes how, after hard work in constant bad weather, they hit upon a pocket with gemmy aquamarines and heliodors in 2011. The crystals measured 2.1–14.2 cm (0.8–5.7 inches). Their surfaces were slightly to moderately etched. Considering the relatively few gemstone occurrences in Western Europe, this find can be regarded as outstanding. The most beautiful crystals are shown in color photos.

Abstracted by Rolf Tatje Source: GIA @topic:1


Title: Bench Tip #1: How To Sharpen A Drill Bit Abstract: How to Sharpen a Drill Bit

Small, fine drill bits used for jewelry making will become dull with normal use. Worn cutting edges make tasks more difficult and time-consuming and can cause costly accidents, including damage to jewelry and gemstones or even injury. Maintaining the cutting surfaces on your tools will ensure clean, consistent work at the bench.

This installment will teach you how to sharpen the cutting edges of a fine drill bit. There are different styles of bit tips, but this example features a chisel tip. Let’s begin with a look at its anatomy.

A drill bit has two cutting surfaces, one on each side of its center axis, that are cut at an angle of approximately 60 degrees.

	The parts of a drill bit.
Notice that each of these angled surfaces is also cut at a slightly narrower angle, creating another plane. This plane creates the cutting edge as well as a relief area behind that edge. This relief area prevents contact with the metal being cut as a hole is drilled, which reduces drag and friction.

The helical groove in the drill bit is called the flute.  It acts as a channel to guide the cut material out of the hole created by the two cutting edges.

We will file each of the relief areas to sharpen the drill bit, maintaining the same angle as these planes, which is important for the drill bit to perform properly after sharpening. The cutting edges will be honed by reducing a small amount of metal from each surface.

	The cutting area and the angle of the relief area plane.
Begin by inserting and tightening a silicon carbide separating disk in a No. 30 hand piece of a flex shaft. Secure the worn drill bit in a screw mandrel and brace against the bench pin as you position the bit to be filed on the relief area.

Carefully lower the separating disk to lightly touch the targeted surface. Without changing the angle, rotate the bit in the holding device and repeat on the opposite relief area plane. Once this is complete, you will have a newly sharpened bit. This may take a bit of practice, but it’s a valuable technique that can save time on the job.

	Always maintain the angle of the relief area plane when sharpening. Source: GIA @topic:7


Title: Inclusions in Kenyan Rubies from the John Saul Mine Abstract: Figure 1. Bands of dense clouds of particles associated with iridescent short needles. Photomicrograph by Suwasan Wongchacree; field of view 1.75 mm.

Rubies from the John Saul mine have been available in the market since the 1970s. The gems are found in a pegmatite-like vein that intrudes an ultrabasic body within the country rock (Winter 1999 Gem News, pp. 213–215). While the mine has produced a large quantity of ruby with fine color, only a small part of the production is fine quality and suitable for faceting, with most of the samples being cut into cabochons. Production has declined, and the material is seen less nowadays.

Figure 2. A negative crystal surrounded by iridescent thin films. Photomicrograph by Charuwan Khowpong; field of view 1.20 mm.
The rubies have an inclusion scene that typically includes short, iridescent needles associated with dense clouds of particles, often in bands (figure 1). Negative crystals surrounded by a plane of thin films are also typical (figure 2). These are very similar to the inclusion scenes in rubies from Mogok (Myanmar) and other marble-hosted deposits. The fact that the color and fluorescence, which is dictated by the trace element chemistry, are also similar to marble-related deposits makes separating them from Kenyan rubies even more challenging. This shows that similar inclusion scenes can form in very different geological environments and that the internal world of gemstones is not always a conclusive indicator of geographic origin. Source: GIA @topic:1


Title: Dutrowite: New Mineral Species of Tourmaline Abstract: Left: Professor Barbara Dutrow has been honored with the naming of the new mineral dutrowite. Photo by Kevin Schumacher. Right: Sample of dutrowite (brown) and dravite (blue) tourmalines in meta-rhyolite from Italy. Courtesy of Cristian Biagioni.
A newly discovered mineral species of the tourmaline group has been named in honor of Dr. Barbara Dutrow (see above, left). Dutrowite (above, right) was discovered in the Apuan Alps of Tuscany, Italy, and has been recognized by the International Mineralogical Association. The Austrian, Italian, and Swedish researchers who discovered the mineral named it in recognition of Dr. Dutrow’s teaching and research contributions, particularly on tourmaline and its formation. She is the Gerald Cire and Lena Grand Williams Alumni Professor in the Department of Geology and Geophysics at Louisiana State University in Baton Rouge. In 2007, she was a coauthor of the 23rd edition of Manual of Mineral Science, a standard reference textbook for the study of minerals. Since 2016, Dr. Dutrow has served on the GIA Board of Governors. Source: GIA @topic:11


Title: The Job Seeker's Handbook Abstract: After many hours of dedicated study at GIA, you’re ready to find your dream job.

But where do you begin? What do you need to do? And how do you stand out from other applicants?

This booklet contains some essential information you’ll need to succeed in your job search. We encourage you to use it as you begin your professional journey.

To download The Job Seeker's Handbook click on "Download PDF" above. Source: GIA @topic:9


Title: Play-of-Color Opal from Wegel Tena, Wollo Province, Ethiopia Abstract: A new opal deposit was discovered in 2008 near the village of Wegel Tena, in volcanic rocks of Ethiopia’s Wollo Province. Unlike previous Ethiopian opals, the new material is mostly white, with some brown opal, fire opal, and colorless “crystal” opal. Some of it resembles Australian and Brazilian sedimentary opals, with play-of-color that is often very vivid. However, its properties are consistent with those of opal-CT and most volcanic opals. Inclusions consist of pyrite, bariummanganese oxides, and native carbon. Some samples show “digit patterns”: interpenetrating playof-color and common opal, resembling fingers. The opaque-to-translucent Wegel Tena opals become transparent when soaked in water, showing a remarkable hydrophane character. White opals from this deposit contain an elevated Ba content, which has not been reported so far in opal-CT. The fire and crystal opals are prone to breakage, while the white, opaque-to-translucent opals are remarkably durable. The proportion of gem-quality material in the Wegel Tena deposit seems unusually high, and 1,500 kg have already been extracted using rudimentary mining techniques. The deposit may extend over several kilometers and could become a major source of gem-quality opal.

	DATA DEPOSITORY

Details of the LA-ICP-MS Analytical Conditions
Chemical Composition of Opals from Wegel Tena, Ethiopia, Measured by LA-ICP-MS
	July 31, 2010 Source: GIA @topic:11


Title: Unusual Growth Zoning in Beryl Abstract: Figure 1. This aquamarine, shown in plane-polarized light, has a dramatic secondary growth layer that is much more saturated in color than the crystal’s primary growth. Photomicrograph by Nathan Renfro; field of view 2.45 mm.

	An aquamarine crystal from Pakistan recently examined by the authors showed a rather dramatic inclusion scene in which several cracks were lined with a vivid blue coloration. We theorize that this relatively pale blue aquamarine developed cracks while in the growth environment. Subsequently, the nutrient solution may have shifted out of equilibrium with the beryl crystal, resulting in a relatively quick dissolution along the cracks. After some period of time, there appears to have been a modification of the nutrient solution and/or growth conditions in which precipitation of beryl became favorable once again. This second generation of growth had a distinctly different trace element composition, resulting in a strongly saturated blue coloration (figure 1) that made the boundary between the primary and secondary growth layers readily apparent (for previously documented examples of second-generation growth, see E. J. Gübelin and J. I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 2, Opinio Verlag, Basel, Switzerland, 2005, pp. 249–250). Chemical analysis by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) confirmed that both zones were in fact beryl and revealed elevated levels of iron in the dark blue layers, which accounts for their darker color (G.R. Rossman, “Color in gems: The new technologies,” Summer 1981 G&G, pp. 60–71). The trace elements Na, Mg, Sc, Ti, V, and Mn were also elevated in the dark blue areas. This dramatic change in chemical composition further supports our theory that there was a significant modification of the nutrient solution in the crystal’s growth environment. This striking specimen shows how complex and dynamic the “birthplaces” of gems can be. Source: GIA @topic:3


Title: Sphalerite in Topaz Abstract: Figure 1. Oblique diffuse illumination reveals the scene within a colorless topaz. Its sphalerite inclusions all feature an isometric crystal habit, metallic luster reflections, and subtle iridescent interface colors. Photomicrograph by Jonathan Muyal; field of view 4.79 mm.

	A 6.54 ct colorless topaz specimen hosting eye-visible dark crystals was examined at GIA’s Carlsbad laboratory. The crystals exhibited a submetallic luster and showed isometric morphology with step-like growth (figure 1). Some also displayed slightly corroded rounded edges with a reflective iridescent interface. The corroded appearance suggested that these dark crystals are protogenetic inclusions that were present in the growth environment before the topaz began to form. Raman spectrometry and LA-ICP-MS analysis confirmed that the inclusions were sphalerite, a zinc-iron sulfide with the formula (Zn,Fe)S. Fluid inclusions were also observed in this topaz.

	Sphalerite has been described in the literature as a collector’s gem for its rarity and beautiful luster (Summer 1992 Gem News, p. 202). This is the first documented example of sphalerite as a crystal inclusion in colorless topaz, making it an unusual collector’s gemstone. Source: GIA @topic:2


Title: Two Unusual Natural Sapphires with Synthetic Ruby Overgrowth Abstract: Figure 1. A thin layer of synthetic ruby overgrowth with flux particles is distinct from the natural sapphire seed visible in the upper right of the image. Photo by Hollie McBride; field of view 1.99 mm.

The New York laboratory recently received two loose red oval mixed cuts for identification. Standard gemological testing yielded refractive indices slightly higher than expected for corundum: 1.778–1.788 and 1.776–1.787, while a typical RI for corundum is 1.762–1.770. Elevated RIs for chromium-diffused corundum have been reported and may be attributed to higher Cr2O3 concentration at the surface (S.F. McClure et al., “Update on diffusion-treated corundum: Red and other colors,” Spring 1993 G&G, pp. 16–28). To the unaided eye, the stones appeared to be chromium diffused, displaying red color concentration at the facet junctions, but their synthetic component became apparent upon further observation.

Microscopic examination revealed that planes of minute particles demarcated a thin layer, approximately 0.3 mm thick, of synthetic overgrowth from a natural sapphire core (figure 1). The presence of intact silk and heat-altered crystal inclusions confirmed the seeds to be natural (figure 2). A series of shallow flux-fingerprints cracking the surface suggested a flux growth process (figure 3). Portions of the near-colorless core could be seen in areas where the overgrowth was cut away during polishing (figure 4). These windows showed a sharp boundary without “bleeding” of the saturated red overgrowth into the near-colorless seed, which is typically observed in chromium-diffused corundum (McClure et al., 1993). The windows into the near-colorless seed also indicate that most or all of the red color is concentrated in the synthetic ruby overgrowth.

Figure 2. A fuzzy heat-altered crystal inclusion commonly referred to as a “snowball” is surrounded by a discoid fracture, proving the natural origin of the corundum seed. Photo by Hollie McBride; field of view 1.26 mm.

Figure 3. Reflective silk inclusions in the natural sapphire seed are visible behind a coarse flux fingerprint in the synthetic ruby overgrowth, which was cut through during the fashioning process. Photo by Hollie McBride; field of view 3.57 mm.

Figure 4. A portion of the near-colorless corundum seed is revealed in an area where the synthetic ruby overgrowth was cut away during fashioning. Photo by Hollie McBride; field of view 10.85 mm.
The overall appearance of the two stones was similar to the now-rare Lechleitner synthetic overgrowth emeralds, which are composed of a near-colorless beryl seed with synthetic emerald overgrowth. A sample with this type of synthetic emerald overgrowth was coincidentally submitted to the Carlsbad laboratory for identification around the same time (figure 5). In addition to emeralds, Lechleitner also experimented with ruby overgrowth on both synthetic and natural corundum seeds (K. Schmetzer and H. Bank, “Lechleitner synthetic rubies with natural seed and synthetic overgrowth,” Journal of Gemmology, 1988, Vol. 21, No. 2, p. 95–101), with the most commonly documented versions containing synthetic seeds (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 2, Opinio Verlag, Basel, Switzerland, 2005, p. 352; Fall 2014 Lab Notes, pp. 242–243).

Figure 5. A thin layer of synthetic emerald deposited on a near-colorless beryl seed, a type of synthetic emerald first marketed by Johann Lechleitner in the early 1960s. Photo by Hollie McBride; field of view 3.57 mm.
Advanced testing on the synthetic ruby overgrowth layer using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) revealed the presence of Cr, Fe, Ga, Mn, Mg, Ni, Ti, Pt, and Zr (table 1). These results, specifically the presence of platinum, are consistent with previously reported synthetic ruby overgrowth (S. Saeseaw et al., “Analysis of synthetic ruby overgrowth on corundum,” GIA News from Research, June 10, 2015). Molybdenum was reported in the primary examination of Lechleitner overgrowth rubies (Schmetzer and Bank, 1988), and its absence here suggests alternative growth conditions for these samples.

Although this is not the first report of synthetic ruby overgrowth on natural sapphire seeds (Schmetzer and Bank, 1988; C.P. Smith, “Diffusion ruby proves to be synthetic ruby overgrowth on natural corundum,” Fall 2002 G&G, pp. 240–248), it marks the first time the New York and Carlsbad laboratories have had them submitted for identification. The resurfacing of these vintage overgrowth synthetics shows that once a material is in the trade, it is here to stay. Source: GIA @topic:3


Title: Guatemalan Jadeite Jade: Rough and Finished Abstract: Figure 1. The rough Guatemalan jadeite jade sold by Yax Tun Minerals included blue, green, and lavender hues, with blue being the most prevalent. Photo by Tao Hsu; courtesy of Yax Tun Minerals.
Jadeite jade is one of the most important aggregate gems in today’s global marketplace, with known sources in Myanmar, Japan, Russia, and Guatemala. Among them, Myanmar is the most legendary and still dominates today’s market. Guatemala, however, has recently reclaimed its status as an important jadeite jade producer (see Z. Huang et al., “‘Ice jade’ from Guatemala,” pp. 26–41 of this issue).
At this year’s 22nd Street show, Yax Tun Minerals (Denver, Colorado) offered a wide range of Guatemalan jadeite jade, including rough pieces in blue, green, and lavender (figure 1). According to owner Luke Miller, the bluish color is the most common and the most desired in the American market. All rough is covered with a “skin” resulting from weathering.

Figure 2. The bluish jadeite jade from Guatemala showed high transparency and a very fine texture (left). Some displayed green veins throughout. A flashlight revealed a slight green tint in some pieces with high transparency and fine texture (right). Photos by Tao Hsu; courtesy of Yax Tun Minerals.
The seller provided a strong flashlight for buyers to assess the quality of the rough, similar to what buyers do at the major jadeite auction in Myanmar. The blue color was quite saturated, while the green and lavender colors were not. The bluish rough showed high transparency and some had green veins running through it (figure 2, left). The green veins also exhibited high transparency (figure 2, right). The lavender rough pieces were of low transparency and had a coarser texture than the other two color varieties (figure 1).
The blue color is characteristic of Guatemalan jadeite jade, which is often called “Olmec blue” in the trade. The Olmec civilization was a Mesoamerican culture revealed by archaeological artifacts. The blue to green-blue jadeite jade mined in Guatemala was prized by the Olmecs from about 1500 to 400 BCE. Mesoamerican cultures that followed, such as Mayan, Zapotec, and Totonac, continued the reverence for jadeite jade. But when the Spanish conquered Mesoamerica in the sixteenth century, their appetite for gold and emeralds contributed to the fall of Guatemalan jadeite jade popularity. Mayan guards kept the jade mine locations secret, and they were not rediscovered until 1974. Since then, Guatemala has been gradually regaining recognition as an important source of jadeite jade.
Finished products offered at the Yax Tun booth included beads, beaded necklaces, bracelets, earrings, and small pendants, polished or carved. Many of the top-quality materials are processed at Miller’s carving studio in Mexico.

Figure 3. This spectacular “Rainbow Luna” dagger features a blade of beautiful Guatemalan jadeite jade that shows the characteristic Olmec blue color and even deeper purplish blue close to the point. Courtesy of Georg Schmerholz.
As Guatemalan jadeite jade gains popularity among both Western and Asian consumers, more gem artists are using this material to show their creativity. World-renowned sculptor Georg Schmerholz brought an outstanding collection of jade to the Tucson Gem and Mineral Show. His latest creation, “Rainbow Luna,” is second in the “Resplendent Quetzal” series, which honors a beautiful bird native to Guatemala. Completed in June 2023, the 14-inch dagger is carved from the finest Guatemalan jadeite jade with a patinated bronze handle (figure 3). Schmerholz’s jade art bridges the two disciplines of sculpture and gemstone carving.
The wide range of appearance and quality of Guatemalan jadeite jade offers versatility to designers, artists, and consumers. Sufficient production and distribution are essential for this gem material to reach a wider audience. Source: GIA @topic:12


Title: Extremely Rare Hellandite Inclusion Found in a Mogok Ruby Abstract: Figure 1. This 0.45 ct oval-shaped ruby, measuring 4.25 × 3.65 × 3.24 mm, exhibited a highly saturated red color. Photo by Huixin Zhao.
Recently, Guild Gem Laboratories (Shenzhen) received a 0.45 ct ruby (figure 1) for origin determination. Standard gemological testing, including a refractive index of 1.762–1.770 and specific gravity of approximately 4.00, and Fourier-transform infrared spectroscopy confirmed its identity as corundum. Additionally, energy-dispersive X-ray fluorescence revealed extremely low iron (247 ppmw) and relatively high chromium (3819 ppmw) and vanadium (448 ppmw) concentrations, consistent with those in marble-hosted samples.

Figure 2. Dense, nested concentrations of silk in the ruby suggest an origin of Mogok, Myanmar. Photomicrograph by Huixin Zhao; field of view 1.13 mm.

Figure 3. A series of irregular calcite crystals in the ruby from Mogok. Photomicrograph by Huixin Zhao; field of view 1.84 mm.

Figure 4. These two transparent brownish hellandite crystals found in a Mogok ruby possibly represent a new ruby inclusion. Photomicrograph by Huixin Zhao; field of view 1.70 mm.
Microscopic observation showed a typical inclusion scene for Burmese ruby from Mogok, including nested concentrations of fine, long to short rutile needles (figure 2) and irregular calcite crystals (figure 3). To our surprise, two transparent brownish crystals (figure 4) were observed. Their slightly corroded state indicated these crystal inclusions’ protogenetic origin. Micro-Raman spectroscopy using 473 nm laser excitation produced some interesting results. Raman analysis showed several distinct peaks at 207, 238, 298, 317, 349, 423, 475, 574, 793, 868, 987, and 1018 cm–1, consistent with those of hellandite according to the RRUFF database (figure 5; see B. Lafuente et al., 2015, https://rruff.info/about/downloads/HMC1-30.pdf). These hellandite inclusions are rarely observed in ruby from any origin.

Figure 5. Raman analysis identified the two transparent brownish crystals shown in figure 7 as hellandite. Spectra are offset for clarity.
Hellandite, a rare borosilicate mineral with the proposed ideal formula of (Ca, REE)4(Y, Ce)2Al2(B4Si4O22)(OH)2, comes in various colors, including colorless, brown, brownish red, gray, green, and yellow. First found in granitic pegmatite in Norway, hellandite belongs to the monoclinic crystal system. Its crystal structure was determined on a specimen from Predazzo, Italy, and described as B4Si4O22 chains parallel to the c-axis (M. Mellini and S. Mellini, “Hellandite: A new type of silicoborate chain,” American Mineralogist, Vol. 62, No. 1-2, 1977, pp. 89–99).
Myanmar’s ruby deposits occur in marbles intercalated with gneisses that are sometimes intruded by granitoids (G. Giuliani and L.A. Groat, “Geology of corundum and emerald gem deposits: A review,” Winter 2019 G&G, pp. 464–489). Therefore, we speculate that hellandite crystals in the granitoids intruding gneiss were captured by ruby when the ruby formed.
To our knowledge, this is the first time hellandite has been observed in ruby. This finding allows for a better understanding of included minerals in the ruby from the geological setting of the Mogok mine. Source: GIA @topic:2


Title: A Unique Omphacite Jade Pendant Abstract: Figure 1. An omphacite jade pendant measuring 68.4 mm tall, shown in reflected light (left) and transmitted light (right). Photo by Tsung-Ying Yang.
In the past decade, omphacite jade with strong to vivid green color has increased in popularity. Especially noteworthy is the high-quality omphacite jade now coming from Guatemala. There are generally two types of omphacite jade. The first, commonly known as “black omphacite jade” (mo cui  in Chinese), is typically opaque to semitranslucent and black to dark green. The second type contains higher chromium content and is usually made into cabochons, tablets, and pendants of 2–3 mm thickness to produce a strong green color and semitransparent appearance.

Figure 2. Comparisons between the Raman spectra of the jade pendant and the spectra of RRUFF database. The results confirmed that the green part of the jade pendant is omphacite and the yellow part is vesuvianite. The stacked spectra are baseline-corrected and normalized.
Recently, a carved pendant measuring 68.4 × 39.9 × 6.4 mm was submitted to the Taiwan Union Lab of Gem Research (TULAB) for identification (figure 1). The pendant was semitranslucent; its color appeared black when viewed under reflected light but dark green and yellow when viewed with transmitted light. Due to the pendant’s uneven surface, its refractive indexes were challenging to measure. The dark green part showed a refractive index of approximately 1.67, and that of the yellow part was around 1.71 (both by spot reading). To further confirm the mineral composition, Raman spectroscopy with 785 nm excitation was performed on the yellow and dark green areas. The spectra were compared with the RRUFF database (Lafuente et al., 2015, https://rruff.info/about/downloads/HMC1-30.pdf) in figure 2, and the results indicated that the main component of the dark green portion of this pendant was omphacite. However, the yellow regions were identified as vesuvianite, constituting approximately 30% of the entire piece. Omphacite jade displaying both dark green omphacite and paragenetic yellow vesuvianite are not common.
From a gemological perspective, this green and yellow pendant is undoubtedly an exceptional case, given the rarity of omphacite jade coexisting with vesuvianite. However, precisely calculating the amounts of omphacite and vesuvianite with destructive X-ray diffraction analysis was not possible. Source: GIA @topic:12


Title: A New Type of Rutilated Quartz Composite Product Abstract: Figure 1. Photos of the rutilated quartz taken in different viewing directions (top view on the left and side view on the right) showed that the sphere was half colorless and half brown. Photos by Shu-Hong Lin.
Rutilated quartz, which refers to natural quartz with rutile needle inclusions, is very popular in Taiwan’s mineral market. Merchants carve rutilated quartz into spheres rather than pendants or cabochons to get higher prices. The value of such spheres depends on the size of quartz as well as the abundance or appearance of its rutile crystals. Since large and well-formed rutilated quartz is quite rare, it is possible to make those of lower quality into doublets with top covers of glass or synthetic quartz.

Figure 2. The microscopic image of the brown part of the rutilated quartz sphere showed yellow, brown, and black mineral particles with an abundance of bubbles. Photomicrograph by Shu-Hong Lin.
Recently, a rutilated quartz sphere was sent to Taiwan Union Lab of Gem Research (TULAB) for certification service. Half of the sphere was colorless and transparent, while the other half was brown and semitranslucent (figure 1). The supplier had informed the client that it was a rutilated quartz polished into a sphere together with its host rock in order to retain the maximum size and the striking rutile inclusions. The colorless and brown parts had refractive indices of 1.54 and 1.55, respectively, and the fluorescence was inert under an ultraviolet lamp. Microscopic observation revealed that the brown part contained yellow, brown, and black mineral particles with a large number of bubbles (figure 2). The specific gravity was 2.35, which is much lower than the specific gravity of quartz. To further confirm the material of the sphere, the colorless and brown parts were analyzed with a Raman spectrometer. The results showed that the former was quartz, and the latter was mainly composed of epoxy resin and quartz (figure 3).

Figure 3. Stacked Raman spectra of the rutilated quartz sphere and epoxy resin revealed that the colorless part (A) was quartz (463 cm–1) and the brown part (B) was mainly composed of epoxy resin (peaks at 637, 822, 1113, 1182, and 1606 cm–1) and quartz. The spectra are baseline-corrected and normalized.
After a series of gemological tests, we concluded that this sphere could be defined as a new type of doublet or composite material of rutilated quartz, in which the brown part mistaken for host rock was in fact epoxy resin mixed with mineral powders. Due to the increasing demand for rutilated quartz spheres in Taiwan, this composite material may not be merely an isolated case. Source: GIA @topic:3


Title: Cat’s-Eye Brazilian Paraíba Tourmaline Abstract: Figure 1. This 0.51 ct Paraíba tourmaline from Brazil displays sharp chatoyancy. Photo by Nuttapol Kitdee.
A vivid shade of tourmaline varying from “neon” blue to greenish blue, caused by copper and manganese, was discovered in Brazil in the 1980s. Recognized as “Paraíba” tourmaline in the gem trade, it is still highly sought after, even though tourmalines exhibiting this “Paraíba” color are now more accessible from localities such as Nigeria and Mozambique.
Recently, GIA’s Bangkok laboratory received a vivid blue tourmaline with chatoyancy (figure 1), weighing 0.51 ct and measuring 5.89 × 4.19 × 2.46 mm. Standard gemological testing resulted in a spot refractive index reading of 1.64 and a specific gravity of 3.05. Microscopic examination revealed diagnostic irregular two-phase inclusions, trichites, and acicular (needle-like) features. The sharp cat’s-eye effect was caused by an included layer of fine parallel growth tubes positioned just above the base of the cabochon. The phenomenon of chatoyancy enhances its rarity and value.
Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) was used to perform an elemental analysis. The sample showed high Cu ranging from 7289 to 10544 ppmw, as well as 9494–10441 ppmw Mn, 114–133 ppmw Ga, 55–65 ppmw Pb, 39–48 ppmw Fe, 14–20 ppmw Zn, and 0.6–0.5 ppmw Sr. The very high concentration of Cu as well as the results for Ga (<250 ppmw), Pb (<100 ppmw), and Sr (<10 ppmw) supported its Brazilian origin (J.E. Shigley et al., “An update on ‘Paraíba’ tourmaline from Brazil,” Winter 2001 G&G, pp. 260–267; A. Abduriyim et al., “Paraíba-type copper-bearing tourmaline from Brazil, Nigeria, and Mozambique: Chemical fingerprinting by LA-ICP-MS,” Spring 2006 G&G, pp. 4–21; Z. Sun et al., “A simplified species classification for gem-quality tourmaline by LA-ICP-MS,” submitted for publication). Copper-bearing tourmaline of this color is typically referred to in the trade as “Paraíba” tourmaline.
Cat’s-eye Paraíba tourmaline is not new, though fewer than 10 have been submitted to GIA laboratories. The combination of well-developed chatoyancy, transparency, pleasing vivid blue color, and Brazilian origin make this a rare and noteworthy gemstone. Source: GIA @topic:11


Title: Apatite “Piñata” Abstract: Figure 1. A 42.92 mm polished sphere with an exposed orange calcite inclusion was fashioned by Dale Carson from fluorapatite recovered from the Yates uranium mine in Otter Lake, Pontiac County, Quebec, Canada. Photo by Elise A. Skalwold.

While gemologists are accustomed to transparent and translucent materials with microscopically visible inclusions, semi-translucent to opaque gems are generally not considered potential hosts of interesting inclusions. Consequently, only the surfaces of these materials are really explored microscopically. This should not dissuade the avid inclusionist from taking the opportunity to look closely at them for unexpected surprises that may be revealed.

Apatite is appreciated for its range of beautiful colors and other optical properties, as well as its morphological characteristics. Most gem apatite is the fluorine end-member of the apatite group known as fluorapatite, or apatite-(CaF). Transparent gem-quality apatite often contains interesting inclusions such as tourmaline, glass, biotite, goethite, hematite, manganese oxide, and pyrrhotite, so it seems logical that the semi-translucent to opaque form would also host inclusions, albeit obscure ones.

The Otter Lake locality in southern Quebec, Canada, is well known for producing aesthetic cabinet specimens featuring elongated prismatic fluorapatite crystals on orangy or pinkish marble matrix, sometimes with deep purple fluorite in the associated mineral assemblage as well. Damaged crystals of limited potential commercial value as faceted gems or mineral specimens may be fashioned into lapidary items such as carvings, cabochons, and spheres (figure 1), or simply find their way into study collections.

A fascinating dark green apatite crystal obtained from Luciana Barbosa of the Gemological Center in Asheville, North Carolina, recently captured our attention. This specimen, from the Yates uranium mine at Otter Lake, measured 31.16 mm in length and weighed 99.21 ct (figure 2).

Figure 2. This 31.16-mm-long fluorapatite crystal was also recovered from the Yates
uranium mine. Photo by Elise A. Skalwold.
What made this crystal interesting was that it had cracked in half along a plane more or less perpendicular to its length, exposing the otherwise unseen inclusions (figure 3). The two spherical inclusions were identified by Raman analysis as brownish orange calcite, the larger of which measured 5.74 mm in diameter (figure 4). Because of its size, this inclusion was probably at least somewhat responsible for the host apatite cracking apart.

Figure 3. Two orange spherical inclusions were exposed when the fluorapatite crystal fractured in half. Photo by Elise A. Skalwold.

Figure 4. The larger inclusion in the apatite, a 5.74 mm sphere of orange calcite, featured
a pair of purple “eyes” on its surface. Upon further analysis, these were revealed to be
fluorite. Photomicrograph by John I. Koivula.
Upon closer inspection and Raman analysis, two tiny deep purple fluorite crystals could be seen perched on the surface of the largest included calcite sphere (again, see figure 4). The resulting bouquet of contrasting colors and the surprising spherical form of the calcite inclusions with purple fluorite “eyes” turned mishap into treasure, reminiscent of breaking open a piñata to find candy within. These calcite spheres are a mineralogical enigma, though current research suggests they formed at high temperature from entrapped carbonate melt (F. Sinaei-Esfahani, “Localized metasomatism of Grenvillian marble leading to its melting, Autoroute 5 near Old Chelsea, Quebec,” master’s thesis, Department of Earth and Planetary Sciences, McGill University, Montreal, 2013).

While providing valuable insights into geological processes, such inclusions in gems and minerals never fail to enrich the day-to-day experience of gemologists and mineralogists. Source: GIA @topic:2


Title: Observations on the Heat Treatment of Basalt-Related Blue Sapphires Abstract: This dark red crystal, presumably pyrochlore, in a Cambodian blue sapphire changed to red-orange with a surrounding partially healed fracture after low-temperature heat treatment. Darkfield and fiber-optic illumination. Photomicrograph by C. Khowpong © GIA, field of view 1.05 mm.

Basalt-related blue sapphires, which typically have a dark color when faceted, can be lightened through low-temperature heat treatment. This treatment is difficult to detect using standard gemological testing and microscopic examination. Researchers from GIA’s Bangkok laboratory sought an approach to identify this treatment. They performed spectroscopy (UV-Vis-NIR, FTIR, and Raman), LA-ICP-MS chemical analysis, microscopic examination, and fluorescence testing on 50 samples before and after heating.

The results are available in a study titled “Observations on the Heat Treatment of Basalt-Related Blue Sapphires” The authors determined that even with advanced testing, it is difficult to separate artificially heated basalt-related sapphires from natural unheated stones. Source: GIA @topic:3


Title: The Cause of Iridescence in Rainbow Andradite from Nara, Japan Abstract: “Rainbow” andradite from Nara, Japan, occurs as relatively small orangy brown crystals that show attractive iridescence in almost the entire range of the spectrum. The material is nearly pure andradite, as determined by its chemical composition and Vis-NIR and specular reflectance FTIR spectra. Microscopy revealed that two different types of lamellar structures appear to be responsible for the iridescent colors. These lamellar structures cause predominantly thin-film interference and most likely diffraction of light. The terms interference and diffraction are explained and correlated to the structure and iridescence observed in these garnets. Source: GIA @topic:2


Title: Aquamarine, Maxixe-Type Beryl, and Hydrothermal Synthetic Blue Beryl: Analysis and Identification Abstract: Aquamarine, Maxixe-type (irradiated) beryl, and two types of hydrothermally grown synthetic blue beryl currently available in the marketplace were investigated by classical gemological methods, chemical analysis, and UV-Vis-NIR and mid-IR spectroscopy. These materials may be conclusively identified by a combination of these techniques. The Maxixe-type beryl (like natural-color Maxixe beryls) is distinguishable by its unusual dichroism, green UV fluorescence (when present), Fe-free chemical composition, and distinctive UV-Vis-NIR spectrum. The hydrothermal synthetic blue beryls can be discriminated from their natural counterparts on the basis of microscopic features, chemical composition, and visible and infrared spectroscopic features. Source: GIA @topic:3


Title: Trapiche Tourmaline from Zambia Abstract: Well-formed crystals of green tourmaline from northwestern Zambia show a growth pattern reminiscent of trapiche emerald/ruby when sliced perpendicular to the c-axis. In fact, such slices were originally encountered in parcels sold as emerald in Zambia. The trapiche appearance most likely originates from skeletal growth, with the pattern formed by a black carbonaceous substance (mostly graphite) that partially filled growth tubes concentrated in three areas: (1) along the three edges of the trigonal pyramids r {101–1} or r’ {011–1 – }, (2) at the interface between the trigonal pyramids and the prism a {112–0}, and (3) between individual growth sectors of the prism a. Spectroscopic and chemical analyses indicate that the tourmaline is uvite that is colored green by a vanadium-related mechanism. To the authors’ knowledge, this is the first occurrence of trapiche tourmaline. Source: GIA @topic:2


Title: The Radioactive Decay Pattern of Blue Topaz Treated by Neutron Irradiation Abstract: A systematic study of 15 neutron-irradiated blue topaz samples was conducted using high-purity germanium (HPGe) digital gamma-ray spectroscopy. The specific activity of the detected radionuclides (134Cs, 182Ta, 46Sc, and/or 160Tb) was measured, and the decay pattern of the irradiated topaz was determined. Based on the time elapsed since their removal from the nuclear reactor, the amount of time required for the residual radioactivity to decay to safe levels was calculated. Most of the samples were safe at the time of the first measurement (95 days after irradiation), but higher concentrations of radionuclide impurities in some samples will require them to be quarantined for several years. Source: GIA @topic:3


Title: Determining Garnet Composition from Magnetic Susceptibility and Other Properties Abstract: Quantitative measurements of magnetic susceptibility combined with RI or SG data can provide an easy and inexpensive way of inferring garnet composition. At the time this technique was first applied to faceted garnets (Hoover et al., 2008), a reference set of samples with well-characterized compositions was not available. GIA subsequently provided 28 garnets and their chemical data determined by electron microprobe for a comparison with end-member compositions calculated from magnetic susceptibility measurements and other properties. The results show that endmember compositions based on microprobe data have error margins similar to most of those derived from directly measured properties. Source: GIA @topic:2


Title: New Find: Blue “Cloud Agates” from Weierbach near Idar-Oberstein, Rhineland-Palatinate Abstract: The agate deposits that formed the basis of the lapidary and cutting industry at Idar-Oberstein until the 19th century are mostly depleted. What reaches the market today is the result of rockhound activities. This article reports on a remarkable find from 2012 along a road construction site at Weierbach, near Idar-Oberstein. Found in a small outcrop of volcanic rocks, the nodules showed diameters of 2–12 cm (0.8–4.8 in.). While agates from Idar-Oberstein generally have a fine banding and pastel tones, most of these agates were not banded but showed cloud-like structures and striking sky blue and red colors. The article contains numerous images of the splendid agates and the deposit.

Abstracted by Rolf Tatje Source: GIA @topic:2


Title: Agates of the Teufelskanzel Near Oberthal, Saarland, Germany Abstract: The “Teufelskanzel” (Devil’s Pulpit), a rhyolitic promontory at Oberthal about 30 km (20 miles) southwest of Idar-Oberstein, is one of the many small agate deposits of the Nahe-Saar Basin. A failed first attempt to mine the agates in 1882 was followed by rather chaotic rockhound activities and the equally unsuccessful decision by the community of Oberthal to take over all mining activities. Finally, digging for agates was generally prohibited, a ban that is still in force.

			The agates generally formed as thunder eggs. They show a very beautiful coloration and often bizarre, picturesque forms that inspire the imagination of the beholder. Many also display a strong green long-wave UV fluorescence, supposedly due to uranyl ions.

			The beauty of the agates and their fluorescence are illustrated by a range of color photos.

Abstracted by Rolf Tatje Source: GIA @topic:2


Title: A Newly Discovered Iridescent Andradite from Inner Mongolia, China Abstract: Figure 1. Iridescent andradite samples (25 ct and 125 ct) from the Lindong area of Inner Mongolia, China. As shown in the left photo, sample G-1 displays iridescence on the (211) plane but not on the (110) plane. Photos by Jiuchang Yang.
Iridescent garnet found in Chifeng City, Inner Mongolia, was recently encountered in the Chinese market. Iridescent garnet was first discovered in 1943 in the U.S. state of Nevada (E. Ingeron and J.D. Barksdale, “Iridescent garnet from the Adelaide Mining District, Nevada,” American Mineralogist, Vol. 28, 1943, pp. 303–312), and it is also found in Mexico and Japan (M.A. Badar and M. Akizuki, “Iridescent andradite garnet from the Sierra Madre Mountains, Sonora, Mexico,” Neues Jahrbuch für Mineralogie - Monatshefte, Vol. 1997, No. 12, pp. 529–539; T. Hainschwang and F. Notari, “The cause of iridescence in rainbow andradite from Nara, Japan,” Winter 2006 G&G, pp. 248–258). To the authors’ knowledge, this is the first report of iridescent garnet in China. Two rough samples were collected by the authors in the Lindong lead mining area (figure 1). The refractive index was over the limits of a conventional refractometer, and the hydrostatic specific gravity values were 3.85 and 3.84. Both showed an inert reaction to long- and short-wave ultraviolet fluorescence. These standard gemological testing results were consistent with garnet.

Figure 2. Left: Growth layers viewed normal to the (110) crystal face in a backscattered electron (BSE) image from a polished thin section. Right: The iron and aluminum contents corresponding to each spot in the BSE image.

Figure 3. Sample G-1 was identified as andradite based on a comparison with a sample from the RRUFF database. Spectra are offset vertically for clarity.
On the basis of energy-dispersive X-ray fluorescence, calcium, silicon, iron, aluminum, manganese, magnesium, titanium, and sodium were detected. The chemical composition of the larger sample was analyzed using electron probe microanalysis (EPMA). The composition was consistent with that of andradite, containing major elements of calcium, iron, aluminum, and silicon, with the derived chemical formula of (Ca3.015Mn0.031Na0.006Mg0.003Ti0.002) (Fe1.846Al0.138)[Si2.978O12]. The backscattered electron image showed clear growth layers (figure 2, left). Aluminum in the darker zones was about 2 wt.% higher on average than in the lighter zones, and the iron content decreased with increasing aluminum. Raman spectroscopic analysis involved comparison with the RRUFF database (B. Lafuente et al., https://rruff.info/about/downloads/HMC1-30.pdf). The peak positions (figure 3) indicated that the samples were consistent with those of andradite, supporting the composition inferred from EPMA. Raman shifts within 300 to 400 cm–1 were assigned to SiO4 rotational vibrations. Raman shifts within 400 to 700 cm–1 were caused by Si-Obend (bridge oxygen) bending and asymmetric stretching vibrations. Raman shifts at 800 to 1200 cm–1 were attributed to the characteristic absorption peak of Si-Ostr stretching vibration (B.A. Kolesov and C.A. Geiger, “Raman spectra of silicate garnets,” Physics and Chemistry of Minerals, Vol. 25, No. 2, 1998, pp. 142–151).

Figure 4. Sample G-1 displays strong iridescence with a full spectrum of colors. For certain bands, the color does not change as the viewing angle changes. This image is of a face parallel to (211). Photomicrograph by Jiuchang Yang; field of view 24.45 mm.

Figure 5. Top: The polished thin section in A and B was cut normal to the (110) crystal face. Observation under crossed polarizers (A) showed strong grid-like pattern, abnormal birefringence (possibly caused by lattice-like twinning), and angled growth bands. Bottom: The section in C and D was cut parallel to the (110) crystal face. Observation under crossed polarizers (C) showed partitioned abnormal birefringence caused by contact twinning and faint growth bands. Photomicrographs by Jiuchang Yang; field of view 25.05 mm.
Microscopic observation revealed an attractive play-of-color with a complete visible spectrum of colors on the (211) crystal plane of sample G-1 (figure 4). We cut three polished thin sections from sample G-2 along the (110) and (211) crystallographic axes to observe the twinning structure and extinction phenomena under a polarizing microscope. The sample displayed angled layered growth structures and a strong grid-like pattern and abnormal birefringence (figure 5). A grid-like extinction phenomenon parallel to the growth layer (figure 5A) may have been caused by lattice-like twins, and figure 5C shows two areas with different extinction orientations. One study on Japanese andradite showed that the iridescence effect is caused by the alternate growth of iron-rich layers and aluminum-rich layers. These layers cause a thin-film interference phenomenon in the crystal structure (Hainschwang and Notari, 2006). Therefore, we speculate that the iridescence of andradite from the Lindong lead mining area is not closely related to twinning but may be closely related to thin-film interference caused by its layered growth structure. Source: GIA @topic:2


Title: Chondrodite in Red Spinel from Mogok, Myanmar Abstract: Chondrodite crystal in a red spinel from Mogok viewed under darkfield, diffuse, and fiber-optic illumination. Photomicrograph by Charuwan Khowpong; field of view 1.05 mm.

Myanmar, formerly known as Burma, is one of the world’s leading sources of gemstones. This includes red spinel with remarkable color, clarity, and appearance. A 1.507 ct red spinel collected from the Thit Saint Kone mining area in Mogok is part of GIA’s research collection. Its inclusion scene is dominated by a single round crystal with small trigons and a rough surface texture (see above). The crystal was identified as chondrodite by Raman spectroscopy. Chondrodite is a magnesium-rich variety within the humite mineral group. This mineral requires relatively high temperature and pressure conditions to form, which are found in the Mogok Metamorphic Belt. Chondrodite forms during contact metamorphism of magnesium-rich limestones and felsic intrusions.
Since chondrodite and spinel are both found in metamorphosed Mg-rich marbles, it makes sense that they occur in association. Nevertheless, the combination of both minerals has rarely been documented in gems and, as such, is a potential indicator of Burmese origin in gem-quality red spinel (M.M. Phyo et al., “Spinel from Mogok, Myanmar—A detailed inclusion study by Raman microspectroscopy and scanning electron microscopy,” Journal of Gemmology, Vol. 36, No. 5, 2019, p. 423). Source: GIA @topic:2


Title: “Flower in the Rain” Inclusion in Sri Lankan Sapphire Abstract: Reminiscent of a flower in a rainstorm, this inclusion scene has been dramatically enhanced using modified Rheinberg illumination to accentuate a growth blockage and thin-film rosette within a sapphire from Elahera, Sri Lanka. Photomicrograph by Jonathan Muyal; field of view 1.34 mm.

The island of Sri Lanka is famous for gems but is also notable for its enormous biodiversity. It therefore seemed fitting that when these authors encountered a fascinating inclusion reminiscent of a beautiful flower within a Sri Lankan sapphire, it would embody these themes.

This 3.64 ct blue sapphire specimen from Elahera exhibited an interesting growth blockage resulting in an elongate tube capped by a rosette-like thin-film fluid inclusion. To further enhance the inclusion scene, Rheinberg illumination (Fall 2015 Micro-World, pp. 328–329) using blue and yellow filters provided additional contrast. This lighting technique transformed the inclusion scene into an easily imagined, vibrantly colored flower caught in a rainstorm, something one might encounter while visiting the tropical island nation (see above).

Growth blockages occur when a foreign mineral grain or particle interrupts the growth of a crystal (Spring 2010 Lab Notes, pp. 55–56). As the crystal continues to grow, an elongate void is typically produced, which may extend to the surface or be capped off, as seen in this sapphire. Even though a growth blockage is not diagnostic of Sri Lankan origin in sapphire, this inclusion scene is an appropriate symbolic representation of the “resplendent isle.” Source: GIA @topic:3


Title: Corundum Carving Coated with Colored Polymer Abstract: Figure 1. This 444 g dark violetish blue carving of Lord Mahaveera, submitted as sapphire, was identified as corundum coated with a blue polymer. Photo by Gagan Choudhary.
Coating, one of the traditional forms of enhancement, is still widely used on a number of gem materials. This contributor alone has reported on recent examples (e.g., Spring 2011 GNI, pp. 71–72; Summer 2012 GNI, pp. 154–155). The latest is a dark violetish blue carving of the early Jain spiritual leader Lord Mahaveera, submitted as sapphire (figure 1), that turned out to be corundum coated with a blue colored polymer.
The 444 g opaque carving measured 10.00 × 8.00 × 4.50 cm. Although it had the heft of sapphire, its dull, vitreous to waxy luster (again, see figure 1) raised doubts. Examination from different directions using a fiber-optic light revealed substantial color variation in different parts of the carving; some areas appeared pale blue, others dark violetish blue. This patchy, concentrated color variation is associated with dyes. Parallel whitish crisscross lines were also observed, consistent with the twinning planes associated with corundum. Further microscopic observation revealed color concentrations within cavities, large fractures, and twinning planes, confirming the material had been dyed (figure 2, left). Finer fractures appeared whitish, however. When the carving was rotated, some areas also displayed a chipped bluish layer on the surface (figure 2, right), an attribute typically found in coated materials. This layer was easily indented with a metal pin, suggesting the presence of a polymer. In addition to these features, the carving possessed a granular texture in many places, as commonly seen in rocks. These grains were also identified as corundum on the basis of the crisscross pattern of their twinning planes, which is consistent with corundum.

Figure 2. Color concentrations within cavities, large fractures, and twinning planes (left) confirmed the presence of a dye. The chipped layer of blue polymer (right) indicates a coating; this polymer layer was easily indented by a metal pin. Photomicrographs by Gagan Choudhary; magnified approximately 20×.
Under UV light (long- and short-wave), the carving displayed patchy white and chalky green fluorescence, mainly on the surface. A desk-model spectroscope revealed weak absorptions at 540, 610, and 640 nm, confirmed with UV-Vis-NIR spectroscopy. Such bands are associated with cobalt-based dyes. RI and SG could not be measured because of the piece’s large size, though visual features were sufficient to identify the carving as corundum. Source: GIA @topic:3


Title: Astrophyllite in Bastnäsite-(Ce) Abstract: Figure 1. This 6.92 mm bastnäsite-(Ce) from Pakistan contains numerous straight and curving acicular inclusions of astrophyllite. Photo by Kevin Schumacher.

	Pakistan’s Zagi Mountains are known as a source for both astrophyllite and bastnäsite-(Ce). The two minerals often grow together, with bastnäsite-(Ce) overgrowing stalks and fibers of astrophyllite; the latter is then sometimes incorporated as inclusions in the bastnäsite-(Ce). We refer to these types of inclusions as “protogenetic.”

	The author recently had the opportunity to examine the brownish orange bastnäsite-(Ce) seen in figure 1. The 1.40 ct oval modified brilliant, provided by Luciana Barbosa (Gemological Center, Asheville, North Carolina), hosted an abundance of eye-visible inclusions of astrophyllite (figure 2), both straight and curved, that were identified by Raman analysis. Some of the included fibers and stalks appear to have been partially altered or coated with iron compounds.

	Figure 2. Magnification affords a more detailed view of the bastnäsite-(Ce) inclusions. Photomicrograph by Nathan Renfro; field of view 2.85 mm. Source: GIA @topic:2


Title: Emeralds from the Kafubu Area, Zambia Abstract: Zambia is considered the world’s second most important source of emeralds by value (after Colombia). The deposits are located near the Kafubu River in the Ndola Rural Restricted Area. Emeralds have been known from this region since 1928, but significant commercial production began only in the 1970s. As of mid-2004, most of the emeralds were being mined from large open-pit operations at the Kagem, Grizzly, and Chantete concessions. Economic emerald mineralization is confined almost entirely to phlogopite reaction zones adjacent to Be-bearing quartz-tourmaline veins that metasomatically altered Cr-bearing metabasite host rocks. Nearly all of the rough is cut in India and Israel. Zambian emeralds have relatively high R.I. and S.G. values, with inclusions typically consisting of partially healed fissures, as well as actinolite, phlogopite, dravite, fluorapatite, magnetite, and hematite. They contain moderate amounts of Cr, Mg, and Na, moderate-to-high Fe contents, and relatively high Cs and Li. Although many features of Zambian emeralds are comparable to those from other commercially important localities, in many cases they may be separated by a combination of their physical properties, microscopic characteristics, and chemical composition.

	DATA DEPOSITORY

Table 1: Local Geological Terminology for the Kafubu Emerald Area
Table 2: Chemical Composition of Zambian Emeralds by Electron Microprobe
Figure: Fluid Inclusions in Zambian Emerald Containing CO2 and CH4

Submitted by Brendan M. Laurs
	August 18, 2005 Source: GIA @topic:2


Title: Infrared Spectroscopy of Natural vs. Synthetic Amethyst: An Update Abstract: When microscopic identification is not feasible, FTIR spectra at high resolution (0.5 cm–1) can distinguish natural and synthetic amethyst. The 3595 cm–1 band is characteristic of natural amethyst and has a full width at half maximum (FWHM) of 3.3 ± 0.6 cm–1. In synthetic amethyst, this band is either absent or (very rarely) about twice as broad. Exceptions to this criterion include natural amethyst with pronounced near-colorless zones, which do not always display this band, and natural specimens that either have an intense, unusually broad 3595 cm–1 band or show total absorption in the X-OH region (3800–3000 cm–1) of the spectrum.

	DATA DEPOSITORY

Additional Figures
	October 24, 2011 Source: GIA @topic:3


Title: Dendritic Inclusions in Cambodian Sapphire Abstract: Figure 1. Fiber-optic illumination reveals dendritic inclusions of a manganese oxide-hydroxide compound trapped within a fracture. Photomicrograph by Charuwan Khowpong; field of view 1.05 mm.

A 0.66 ct piece of blue sapphire rough from the Bo Tang Su mining area of Cambodia’s Pailin region displayed dendritic inclusions, commonly found in quartz and chalcedony but rarely seen in corundum.

These epigenetic inclusions occur as a dendritic pattern trapped along surface-reaching fractures and show higher luster than the host under reflected light. Viewed in fiber-optic light, they appear black along the fracture and the trapped unknown fluid phases (figure 1). Raman spectroscopy identified the inclusions as a compound of manganese oxide-hydroxides. The presence of these dendritic inclusions, seen trapped in a triangular fracture in figure 2, is quite unusual in sapphire from Cambodia.

Figure 2. The dendritic inclusions were trapped in a triangular fracture. Photomicrograph by Charuwan Khowpong; field of view 1.75 mm. Source: GIA @topic:3


Title: Demantoid and Topazolite from Antetezambato, Northern Madagascar: Review and New Data Abstract: An important deposit of andradite, containing demantoid and topazolite varieties, has been mined near the village of Antetezambato in northern Madagascar since early 2009. Most of the activity took place from April through November 2009, and yielded a large quantity of rough material in a wide range of colors. The deposit has a skarn origin, related to contact metamorphism between Cenozoic magmatic intrusions and Mesozoic calcareous sediments. The garnets’ internal features consist mainly of fluid inclusions, fractures, wollastonite needles (or their remnant channels), and diopside aggregates. The chemical composition is close to pure andradite, with negligible Cr and V contents; thus, iron is likely the main chromophore. LA-ICP-MS analysis showed a relatively high content of light rare-earth elements.

	DATA DEPOSITORY

Rare-Earth Element Composition
	May 2, 2011 Source: GIA @topic:11


Title: Chalcedony with Quartz Windows Abstract: The trigonal windows of quartz found throughout this translucent white chalcedony displayed vibrant interference colors when examined between crossed polars. The black triangles in the lower left corner are also quartz. Photomicrograph by John I. Koivula; field of view 15.5 mm.

	A translucent white chalcedony specimen containing a few small transparent quartz crystals was fashioned into a decorative polished plate by Falk Burger (Hard Works, Tucson, Arizona). One intriguing feature of this piece is that most of the transparent quartz crystals were aligned with their c-axes parallel to each other. When they were transected perpendicular to this axis during the polishing process, angular transparent windows were created, each displaying trigonal symmetry within their otherwise translucent chalcedony host. Interestingly, even though the white chalcedony was polished into a plate, it still showed a rather curious angular-looking three-dimensional texture. When examined between crossed polars, the triangular quartz windows ignited with vibrant interference colors, as seen in the accompanying image, due to Brazil-law twinning in the crystals. Source: GIA @topic:2


Title: Peridot, Pyroxene, and Plagioclase: Mantle Megacrysts from Lunar Crater Volcanic Field in Nevada Abstract: Megacrysts within xenoliths transported by explosive volcanic eruptions to the surface are fingerprints of the earth’s upper mantle and possible collectors’ items.

Lunar Crater is located in Nye County, Nevada. It is a Quaternary alkali basaltic field with lava flows, cinder cones, and maars covering more than 100 square miles of Nevada desert. At numerous alkali basaltic volcanic fields in the western United States, ultramafic mantle xenoliths of peridotite, dunite, lherzolite, and monomineralic xenocrysts are found in lunar craters. Olivine, pyroxene, plagioclase, hornblende, and magnetite ranging from a few millimeters to centimeters are common megacrysts. These megacrysts are usually ejected from the volcanic vent as the cores of volcanic bombs. Bomb morphology can vary considerably due to different viscosities of lava. While these magacrysts can provide scientific information on the upper mantle composition, the authors are interested in their possible gemological significance. Peridot, the green variety of olivine, is reported to occur in nodules up to 50 cm. But the crystals are highly fractured, making them unfit for faceting. Plagioclase crystals from the lunar crater can be clear to translucent white and show typical feldspar twinning. Pyroxene megacrysts found in the lunar crater are usually the augite variety and apple green, bottle green, or nearly black.

Minerals in the Lunar Crater volcanic field are abundant and easily accessed. Volcanic bombs contain exotic xenocrysts of possible gem significance, making this a worthy destination for rock hunters.

Abstracted by Tao Hsu Source: GIA @topic:1


Title: Raspberry-Red Garnet with Black Core Abstract: Figure 1. A very fine 4.5 × 3.1 × 2.1 cm specimen of raspberry-red grossular from skarn deposits, with crystals approaching 1 cm. The matrix consists of calcite, quartz, wollastonite, and scapolite. Photo by Kevin Schumacher.

Raspberry-red grossular garnet mineral specimens have been popular in the collector  market since their discovery in 1994 in the Sierra de Cruces range in the State of Coahuila, Mexico. V.W. Lueth and R. Jones (“Red grossular from the Sierra de Cruces, Coahuila, Mexico,” Mineralogical Record, Vol. 34, No. 6, 2003, p. 73) described the geological environment where the garnet was discovered and the petrological composition of the garnet and matrix (figure 1). An interesting internal characteristic of this type of grossular crystal is its raspberry-red rim and black core with sharp color transition at the core-rim boundary. Lueth and Jones reported that the raspberry-red rim is composed mainly of grossular and the black core contains up to 4.5 wt.% titanium that can be used to calculate additional morimotoite and schorlomite garnet end-member  species (table 1). No detailed chemical analysis of the black core was presented, however. To better understand the composition of this type of garnet, we prepared a thin section sliced from the middle of one garnet crystal (see the color-zoned image in the middle of figure 2) for detailed chemical analysis at GIA’s Carlsbad laboratory.

TABLE 1. Cation site occupancies for garnet end members.

Figure 2. Garnet end-member percentage vs. position profile revealed that the black core of the garnet was rich in morimotoite and schorlomite. The pink rim of the garnet was composed almost entirely of grossular with minor andradite.

The section’s chemical composition was obtained with a Thermo Fisher iCAP Q ICP-MS coupled with a New Wave Research UP-213 laser ablation unit. 29Si was used as the internal standard. GSD-1G and GSE-1G were used as external standards. A line of 33 ablation spots was selected to cross the whole section from one outer rim to the opposite outer rim. The black core contained up to 27.91 mol.% morimotoite and up to 4.07 mol.% schorlomite (figure 2). The detailed composition of the black core of spot 7 to spot 15 (the light blue vertical zone in figure 9) is listed in table 2. The black core contained 4.10–5.04 wt.% TiO2, confirming the analytical results reported by Lueth and Jones, and 4.42–5.49 wt.% FeOtot. It also contained 0.26–0.84 wt.% ZrO2 that could be used to calculate a distinct kimzeyite garnet end-member species (tables 1 and 2; table 1 gives the composition and site occupancy of the end members). It is the first time a detailed chemical analysis of the black core of this type of raspberry-red garnet has been documented.

TABLE 2. Chemical composition of grandite-morimotoite garnet spots by LA-ICP-MS. Source: GIA @topic:2


Title: Hyalite with Magnificent Internal Features Abstract: Figure 1. Purple fluorite cube, identified by micro-Raman spectroscopy, in a hyalite. Photomicrograph by U. Hennebois; field of view 1.2 mm.
The Laboratoire Français de Gemmologie (LFG) received for analysis a 1.83 ct hyalite, also known as opal-AN: an amorphous (A) opal containing hydrated silica molecules that are network forming (N) (E. Fritsch et al., “Green-luminescing hyalite opal from Mexico,” Journal of Gemmology, Vol. 34, No. 5, 2015, pp. 490–508). This is one of the rarest varieties of gem-quality opal. The gem fluoresced green under long-wave ultraviolet (365 nm) and, with more intensity, under short-wave UV (254 nm), due to U6+ in the form of uranyl (UO2)2+ (E. Gaillou et al., “Luminescence of gem opals: A review of intrinsic and extrinsic emission,” Australian Gemmologist, Vol. 24, No. 8, 2011, pp. 200–201). A purple fluorite (identified by a micro-Raman spectrometer; figure 1) and a series of cube-shaped cavities were visible (figure 2) in the hyalite, which appear to be all interconnected. Sometimes these cavities also contain small crystals of fluorite relics detected by Raman. Thus, these cavities may be the result of the partial dissolution of fluorite crystals. This would explain their cubic morphology, which cannot be explained by the dissolution of amorphous hyalite.

Figure 2. Interconnected cavities observed in a hyalite containing partially dissolved fluorite relics identified by Raman spectroscopy. Curved growth layers are also observed in the background. Photomicrograph by A. Delaunay; field of view 2 mm.
Between crossed polarizers, high-order interference colors were observed (figure 3), as expected for this gem. This is due to anomalous birefringence linked with the strain present between the curved growth layers of hyalite. Also, a fluid inclusion was observed in the intersection of the botryoids (again, see figure 3). This inclusion is composed mostly of gas, suggesting that this hyalite was deposited from a gaseous phase. Although some of these features have been previously observed in hyalite, it is rare to see them all in the same sample. To the best of our knowledge, this is the first reporting of pronounced cubic cavities in hyalite.

Figure 3. This fluid inclusion contains mostly a gaseous phase. It is trapped at the intersection of curved botryoidal growth zones and presents high-order interference colors obvious between crossed polarizers. Photomicrograph by U. Hennebois; field of view 1 mm. Source: GIA @topic:11


Title: Golden Coral Imitated by Plastic Abstract: Figure 1. These photos compare the appearance of golden coral (left) and a plastic imitation (right). Photo by Lai Tai-An Gem Lab.

As one of the seven Buddhist treasures, coral is a symbol of importance in Chinese culture. Golden-colored coral is considered “sublime,” since both red and gold represent prosperity and prestige. Golden coral, which is usually treated black coral, can be identified by its appearance and structure, with concentric growth layers and a pitted texture (figure 1, left). Imitations lack these characteristic features, which is of relevance to those deal with coral.

The Lai Tai-An Gem Laboratory in Taipei recently received a bracelet for identification; the client claimed the material was golden coral. The bracelet was composed of several evenly sized bright gold to deep brown beads, strung together with thread, that exhibited a waxy luster and an interesting “swirl” pattern (figure 1, right). Identical spot RIs of 1.55 were obtained from each bead, and there was no reaction under LW or SWUV light. The material did not exhibit the characteristic pitted texture of golden coral. Further analysis by FTIR and Raman spectroscopy identified the beads as plastic (resin). Peaks at 2934, 2862, 1731, 1285, 1128, 1072, 745, and 703 cm–1 in the infrared spectrum (figure 2) and peaks at 619, 649, 1000, 1038, 1448, 1578, 1599, and 1725 cm–1 in the Raman spectrum (figure 3) were indicative of plastic. Further inspection at 60× magnification with high-intensity fiber-optic illumination showed that these translucent beads had the same swirl texture extending to the center from the surface, indicating that they were composed of plastic. The aforementioned natural characteristics were not seen at all in this material.

Figure 2. FTIR analysis reveals the difference between the spectra for a tested coral
sample (red line, peaks at 3277, 2936, 1657, and 1543 cm–1) and plastic (blue line, peaks
at 2934, 2862, 1731, 1285, 1128, 1072, 745, and 703 cm–1).

Figure 3. Raman analysis (excitation wavelength of 785 nm) confirmed the beads’ identity
as plastic.
Golden coral may possess a degree of instability, so some material is coated with resin to strengthen the structure. In this case, however, each bead was entirely formed of plastic made to imitate golden coral. Plastics, along with glass, are among the most adaptable materials and can be fabricated to imitate virtually any natural material imaginable. Some imitations are more difficult to identify than others, but in this example identification was fairly simple owing to the structural differences of the two materials, observed with either a microscope or a loupe. Source: GIA @topic:12


Title: Topaz Crystals in Red Beryl Abstract: Figure 1. A 0.22 ct emerald-cut red beryl (5.08 × 3.12 × 1.91 mm). Photo by Huixin Zhao.
Gem-quality beryl comes in various colors, including green, yellow, pink, and rarely red, which has only been mined in the state of Utah to date. Recently, a red beryl (figure 1) was submitted to Guild Gem Laboratories in Shenzhen for identification. This emerald-cut sample weighed 0.22 ct and exhibited a highly saturated red color. The refractive index values of 1.562–1.569 and birefringence of 0.007 were consistent with beryl. Multiple analytical methods were applied, including FTIR and UV-Vis-NIR spectroscopy, and EDXRF for chemical analysis. FTIR confirmed the sample as beryl (figure 2), and the UV-Vis-NIR spectrum showed a prominent manganese-related broad band centered at 540 nm, as well as a weak iron-inducted band at 370 nm (figure 3).

Figure 2. The infrared reflectance spectrum confirmed the identity of the red beryl.

Figure 3. The UV-Vis-NIR spectrum of the red beryl shows a weak peak at 370 nm (Fe3+) and an intense peak at 540 nm (Mn3+).
EDXRF results showed that the beryl was rich in iron (16920 ppm) and manganese (2586 ppm), along with a trace amount of zinc (787 ppm). Such results were very close to previously reported values for red beryl from the Wah Wah Mountains of Utah: 15000 ppm iron, 2000 ppm manganese, and 700 ppm zinc, respectively (J.E. Shigley and E.E. Foord, “Gem-quality red beryl from the Wah Wah Mountains, Utah,” Winter 1984 G&G, pp. 208–221).

Figure 4. Exposed crystal inclusions in the red beryl showed a fine columnar shape and distinct cleavage fissures. Photomicrograph by Huixin Zhao; field of view 1.6 mm.

Figure 5. The Raman spectrum of the crystal inclusion agreed with the topaz spectrum in the RRUFF database.
Microscopic observation revealed several two-phase fluid inclusions along the healed fissures, and purple-blue flashes were clearly seen within the open fissures, which indicated clarity enhancement by organic fillers. This was confirmed by FTIR, with peaks at 2854, 2871, 2927, and 2963 cm–1. Two transparent crystal inclusions were present and exposed to the surface near the girdle, showing a prismatic crystal habit (figure 4). Within the included crystals, a series of cleavage layers were prominent. Further testing by micro-confocal Raman spectroscopy in the 100–1200 cm–1 range showed distinct peaks at 240, 267, 285, 332, 430, 456, and 927 cm–1, results that agree with topaz according to the RRUFF online database (figure 5).
Topaz rhyolites are widely distributed across the western United States, and red beryl occurs in topaz-bearing rhyolites (J.E. Shigley et al., “Red beryl from Utah: A review and update,” Winter 2003 G&G, pp. 302–313). Hence, it is not surprising to see topaz as a mineral inclusion in red beryl, although such an observation does not appear to have been reported before. Source: GIA @topic:3


Title: Spectral Analysis of Resin Imitation Ivory Abstract: Figure 1. The “ivory” items submitted for identification: a bracelet (left) consisting of 16 beads, 13.4 mm diameter each, and two seal stamps (right) measuring 20 × 80 mm each. Photos by Lai Tai-An Gem Lab.
The application of spectroscopic techniques in solving gemological challenges is becoming more routine since more data is needed than standard gemological testing can provide. For example, resin is composed of a variety of complicated chemical components and, while basic testing can identify whether the material is resin, further detailed examination must be undertaken to obtain the specific chemical composition.
A client submitted three “ivory” items for identification, a bead bracelet and two seal stamps (figure 1). This case is similar to the “resin imitation ivory with a pseudo ‘engine-turned’ structure” reported previously (Fall 2019 Lab Notes, pp. 419–421). Standard gemological testing revealed an RI of 1.54 (spot) and an SG of 1.23, with parallel linear striations, all very similar to the properties obtained from the samples in the case referenced above. Natural ivory normally indicates an RI of 1.54 (spot) and an SG of 1.85, with Schreger lines. By comparing with this case, further examinations were taken by the following procedures.
FTIR and Raman spectroscopy were used to analyze the differences between resin imitating ivory and natural ivory reference samples with a known provenance. These results were compared with those of the client’s submissions.

Figure 2. FTIR spectra of natural ivory (top) and this object “resin imitation ivory” (bottom) revealed different peaks.
As shown in figure 2 (top), mid-FTIR reflectance spectra from the natural ivory of known provenance revealed peaks at 1044, 1447, and 1559 cm–1 (related to biogenic hydroxyapatites); 1658, 2850, and 2919 cm–1 (consistent with collagen); and 3310 cm–1 (from CO32–) (Z. Yin et al., “A comparison of modern and fossil ivories using multiple techniques,” Spring 2013 G&G, pp. 16–27). The client’s resin imitations revealed peaks at 702, 1126, 1284, 1380, 1462, and 1730 cm–1, characteristic of ester group alkyd resins (figure 2, bottom) (S.M. Cakić et al., “Investigation of the curing kinetics of alkyd-melamine-epoxy resin system,” Progress in Organic Coatings, Vol. 73, No. 4, 2012, pp. 415–424), and 2932 cm–1, consistent with CH stretching. These results were significantly different from those obtained from known samples of ivory, as detailed above.

Figure 3. Raman spectra comparing natural ivory (top) and “resin imitation ivory” (bottom) also revealed significant differences.
Raman analysis of the natural ivory revealed peaks at 428, 586, 852, 961, 1244, and 1664 cm–1 (figure 3, top), whereas the submitted resin samples displayed peaks at 621, 650, 1001, 1038, 1162, 1186, 1449, 1599, and 1724 cm–1 (figure 3, bottom). The spectra from each were sufficiently different to allow a quick and accurate separation.
These spectral comparisons provide readers with a reference when separating ivory from some resins. However, it is still important to apply standard gemological testing techniques during the initial examination while staying alert to the continual developments likely taking place with resin imitations. Spectral analysis plays an essential role in the differentiation process, especially in cases where more care may be needed. Source: GIA @topic:12


Title: New Plastic Imitation Opal from Kyocera Abstract: Figure 1. This new plastic opal imitation (left) shows a very pleasing play-of-color that does not have the classic "snakeskin" columnar structure one would expect to see in traditional polymer-impregnated synthetic opal produced by Kyocera (right). The largest sample of plastic imitation opal in the left photo weighs 227 grams, and the largest sample of synthetic opal in the right photo weighs 65 grams. The rectangular black block in the photo on the left is 9.7 cm in length. Photos by Robert Weldon.
Recently, the Carlsbad laboratory examined an interesting new gem material manufactured by the Japanese company Kyocera that displayed a play-of-color phenomenon. In the trade, this material may be sold as an “opal-like product,” because of the play-of-color phenomenon observed (figure 1, left).

Standard gemological testing revealed a hydrostatic specific gravity (SG) of 1.35. The refractive index (RI) was measured as 1.49. According to GIA, an imitation is defined as a natural or manmade material that mimics the appearance of, and is used as a substitute for, another gem material. Likewise, a synthetic gem is defined by GIA as a laboratory-grown gem material with virtually the same chemical and physical properties as a natural gem. Because the gemological properties for this new material are out of range for natural opal (SG of 2.00 and RI between 1.37 and 1.47), it is best described as an imitation opal.

Figure 2. The infrared absorption spectrum of the new plastic imitation opal (red trace) was very similar to that of traditional plastic-impregnated synthetic opal (blue trace) except that the polymer feature at ~1734 cm–1 was about five times as strong.
Further testing revealed that this material readily burns with a hot point and produces a strong acrid odor indicating that a significant amount of plastic is present. Additionally, advanced testing using energy-dispersive X-ray fluorescence (EDXRF) spectroscopy revealed the presence of silicon. Fourier-transform infrared (FTIR) testing revealed a spectrum that was quite similar to traditional polymer-impregnated synthetic opal (figure 1, right) except for a polymer peak that was nearly five times as strong (figure 2). These tests indicate that this material is composed of both plastic resin and silicon. When exposed to ultraviolet light, samples with a white bodycolor fluoresced a weak blue to short-wave and medium blue to long-wave UV. Samples with a black bodycolor fluoresced a weak orange to short-wave UV and were inert to long-wave UV.

Figure 3. Traditional synthetic opal shows a "chicken wire" or "snakeskin" pattern (left) and a columnar structure (right) that are diagnostic of synthetic origin. The new plastic opal imitation does not show these features. Photomicrographs by Nathan Renfro; fields of view 7.20 mm (left) and 14.40 mm (right).

Figure 4. Randomly oriented patches of play-of-color are uniformly distributed throughout this new plastic opal imitation. The imitation looks the same from all different angles. Photomicrograph by Nathan Renfro; field of view 13 mm.
Microscopic examination revealed some interesting features. The pattern in the play-of-color was random and unlike traditional synthetic opal did not display any “snakeskin” or “chicken wire” pattern (figure 3, left), but instead showed colored polygonal patches about 2 mm in size uniformly distributed throughout (figure 4). Nor did the plastic imitation opal display the columnar structure one would expect to see in synthetic opal (figure 3, right).

Visually, this new material is a very good imitation of natural opal. Gemologically, it is easy to separate from natural opal due to the comparatively high refractive index and low specific gravity. There are other possible decorative applications for this plastic opal imitation material due to the large sizes that can be produced. This attractive material is a welcome addition to the gem trade and is easy to separate from natural opal with standard gemological testing. Source: GIA @topic:11