Publication Year: 2023 Title: The Special Color Effect in “Chameleon” Amber Abstract: Figure 1. A good-quality 88.25 ct “chameleon” amber with a red bodycolor displaying a vivid green fluorescence color that appears to float on the surface. Photo by Yan Li.

Figure 2. A and B: A 78.51 ct chameleon amber exposed to white light against white and black backgrounds. C and D: A 12.50 ct brownish reference sample exposed to similar lighting and backgrounds. Photos by Jinfeng Yang.
One special variety of Burmese amber is “chameleon” amber, named for the bluish green color that appears to float on its surface (figure 1). This material is found in the famous Tengchong market in Yunnan Province, China’s largest Burmese amber market. Its bodycolor ranges from golden brown to brownish red or even red (figure 2A). When exposed to sunlight or strong white light against a black background, its surface shows a uniform green color (figure 2B). Chameleon amber is rare and expensive compared to regular Burmese golden or brownish amber, especially with the severe reduction of exports from Myanmar.
Until recently, few studies have been conducted on chameleon amber. X. Jiang et al. speculated that the green surface color might be caused by the superposition of its bodycolor and the fluorescence of amber (“Gemmological and spectroscopic characteristics of different varieties of amber from the Hukawng Valley, Myanmar,” Journal of Gemmology, Vol. 37, No. 2, 2020, pp. 144–162). C.C. Shuai et al. proposed that the “light retention” effect was related to elevated sulfur and calcium contents (“The spectrum characteristic research of color change effect and ‘light tarry effect’ amber from Burma,” Spectroscopy and Spectral Analysis, Vol. 40, 2020, pp. 1174–1178). Z. Shi et al. reported that the effect might be due to unique internal aromatic hydrocarbon structures (“Spectral characteristics of unique species of Burmese amber,” Minerals, Vol. 13, No. 2, 2023, article no. 151).

Figure 3. A and B: A 71.05 ct Burmese chameleon amber and its bluish white fluorescence under long-wave UV light. C and D: 16 mm brownish Burmese amber beads (12.60 ct on the left, 12.16 ct on the right) and their bluish purple fluorescence under long-wave UV. Photos by Jinfeng Yang.
For this study, three Burmese chameleon amber specimens were acquired from the Tengchong market (see figures 1, 2A, and 3A). All three displayed a translucent brownish red bodycolor, with a few bubbles and flow lines within them. The bluish green floating color was observed when the specimens were rotated. This phenomenon is most obvious with a black background. Standard gemological properties and Fourier-transform infrared spectroscopy data were consistent with those of regular Burmese amber. While the bluish green floating color might be related to fluorescence, no such effect is seen on other types of fluorescing Burmese amber (e.g., brownish amber). To further explore this, brownish Burmese amber beads with bodycolor similar to that of chameleon amber were selected as a reference (figures 2C and 3C). Their bodycolor was not as vivid as chameleon amber, and it did not display the bluish green floating fluorescence. Observation under a UV lamp showed that the chameleon amber in figure 3A produced strong bluish white fluorescence (figure 3B) in long-wave UV (365 nm), while the brownish amber beads in figure 3C showed a weak bluish purple fluorescence (figure 3D).

Figure 4. 3D fluorescence spectra of Burmese chameleon amber (A) and brownish amber (B).
The samples were then examined with 3D fluorescence spectroscopy (figure 4) under the excitation of a continuous-wavelength excitation light source. The fluorescence intensity of brownish amber was clearly much lower than that of chameleon amber. In addition, two peaks (455 and 384 nm) were absent in the excitation spectrum of brownish amber. A high degree of similarity was exhibited in the samples’ emission spectra, with all the peaks positioned at approximately 434, 464, 469, and 497 nm. However, the biggest difference was in the fluorescence intensity, which was easily observed in chameleon amber.
The 3D fluorescence spectra of chameleon amber exhibited several fluorescence centers, mainly at 434, 464, 469, and 497 nm generated by excitation wavelengths of 386, 406, 436, and 457 nm. The fluorescence color could be calculated by the fluorescence centers, and the results showed that the spectral color was blue under 386 nm excitation and bluish green under 436 nm excitation. We believe that the bluish green floating color under sunlight is caused by the bluish green fluorescence center at 469 nm under 436 nm excitation. This is much more consistent with observations in daylight. Due to the low fluorescence intensity of brownish amber, its blue fluorescence color is very weak, and most light penetrates it without producing any special optical effect. The difference in fluorescence intensity between the 469 and 434 nm fluorescence centers corresponds with the relative spectral power distribution of the light source. Under the excitation of a xenon lamp, the fluorescence center at 434 nm is more intense than the light-emitting center at 469 nm. However, amber is usually observed in daylight. The optimal excitation wavelengths for the emission centers at 434 and 469 nm are 386 nm and 436 nm, respectively. From the relative spectral power distribution of the two light sources, it can be seen that the spectral density of the xenon lamp at 386 nm is greater than 436 nm, while the D65 daylight-equivalent source is the opposite. Against a dark background and under daylight, the fluorescence of chameleon amber should be dominated by the bluish green fluorescence emitted at 436 nm.
The fluorescence center at 469 nm is very common in Baltic, Dominican, Mexican, and Burmese amber. This fluorescence center in chameleon amber is unique for its high intensity and separation from other fluorescence colors. Only if the fluorescence intensity is high enough will it show as the dominant fluorescence color. The optimal excitation wavelength (436 nm) corresponding to the 469 nm fluorescence center is far removed from the optimal excitation wavelength of other strong fluorescence centers; therefore, the fluorescence color is not a mixture of multiple colors. Many varieties of amber can also produce strong fluorescence at 469 nm, but often mixed with other fluorescence colors of similar intensity. For example, the fluorescence peaks of 448 and 474 nm in Dominican blue amber always appear together, and their strong fluorescence peaks can be seen with exposure to the same excitation wavelength. In most cases, the fluorescence intensity of the former is slightly greater, which leads to the fluorescence of the blue amber being mainly blue, without a green modifier. Some Dominican blue amber with uneven fluorescence distribution can also show a mosaic pattern (X. Chenxing et al., “Characterisation of patchy blue and green colouration in Dominican blue amber,” Journal of Gemmology, Vol. 37, No. 7, 2021, pp. 700–713). The fluorescence distribution of the chameleon amber tested in this study was uniform, with high intensity and good separation, producing a high-quality bluish green floating fluorescence effect. @chapter:37


Publication Year: 1988 Title: Examination of Three-Phase Inclusions in Colorless, Yellow, and Blue Sapphires from Sri Lanka Abstract: Three-phase inclusions in untreated natural colorless, yellow, and blue sapphires from Sri Lanka were found to consist of liquid and gaseous carbon dioxide as well as needle-like to tabular crystals of diaspore. The identification of diaspore was accomplished through the use of a microscope-mounted drill system and an improved version of the Gandolfi X-ray camera. Technical details for both methods are given. The conditions under which diaspore forms as a daughter mineral in corundum are briefly discussed. @chapter:19


Publication Year: 2014 Title: Unusual Optical Effect in Blue Sapphire Abstract: Figure 1. This 1.36 ct light bluish violet sapphire displayed an interesting color shift when exposed to the UV radiation of the DiamondView. Photo by Igor Iemelianov; magnified 15×.

              A 1.36 ct light bluish violet sapphire (figure 1) was presented to the laboratory of the State Gemological Center of Ukraine for examination. The stone exhibited an RI of 1.762–1.770, with a birefringence of 0.008, and a hydrostatic SG of 3.97. The samples displayed typical pleochroism and a very weak pinkish orange fluorescence to long-wave UV. Qualitative analysis using EDXRF spectroscopy showed major amounts of Fe, Cr, and Mg, and minor amounts of Ti and Ga. Microscopic examination revealed dot-like dissolved rutile, proof of heat treatment. The sapphire showed a small color shift from bluish violet in the daylight to pale blue in incandescent light. A band with pink luminescence (apparently due to Cr3+ impurity) was identified using the DiamondView (figure 2). When removed from the DiamondView, the stone had completely changed color to brown (figure 3, left). After about 15 minutes in natural daylight, the light bluish violet hue began to return (figure 3, right). About 12 hours later, its original blue-violet color was restored. Such color instability is extremely unusual in blue sapphires.

	Figure 2. The DiamondView recorded this band with pink luminescence in the light bluish violet sapphire. Image by Igor Iemelianov.

	Figure 3. When removed from the DiamondView, the sapphire had completely turned brown (left). After about 12 hours, the stone reverted to its original light bluish violet color (right). Photos by Igor Iemelianov, magnified 15×.
It should be noted that the UV lamp in the DiamondView has a wavelength less than 225 nm (according to the user’s manual). The energy of UV radiation is considered too weak for the color treatment of corundum (see K. Nassau, Gemstone Enhancement, Butterworth-Heinemann, 1984, p. 221). In this sapphire, the DiamondView apparently caused the color change. Such a reversible change of color with exposure to light is called photochromism. @chapter:12


Publication Year: 2023 Title: New Tourmaline Pockets in San Diego County’s Pala District Abstract: Figure 1. A 16.96 ct emerald-cut green tourmaline from rough found near a new pocket at the Tourmaline King mine. Photo by Robert Weldon; courtesy of Pala International.
At the AGTA show, Bill and Carl Larson (Pala International, Fallbrook, California) shared details about new pockets uncovered at the Tourmaline King mine. The first was discovered in January 2022—the first major find at the mine in more than a hundred years, and the first in Southern California since the “Big Kahuna” pocket at the Oceanview mine in 2010. “We’ve hit off and on three or four pockets, some of which are very good,” Bill said.

Figure 2. Rubellite tourmaline rough (440 g) from one of the Tourmaline King mine’s new pockets. Photo by Robert Weldon; courtesy of Pala International.
The Larsons showed us several stones, including a 16.96 ct emerald-cut green tourmaline (figure 1) from rough found near the first pocket in 2022. Bill said the green tourmaline is relatively uncommon for the Pala District. “The green has actually been transparent enough to facet,” Carl added. “That’s been the best material so far.” The new pockets have also produced about 3 kg of fine-color rubellite rough (figure 2).
The Tourmaline King mine’s main tunnel produced eight tons during San Diego County’s massive output of tourmaline in the early nineteenth century, which also involved the Pala District’s Tourmaline Queen, Pala Chief, and Stewart mines, as well as Mesa Grande’s Himalaya mine. (There was a resurgence of mining at Pala in the 1970s.)
Around 1920, mine owner R.M. Wilke and his crew installed a new tunnel below the main one. “They hit this very dangerous zone right before they hit the pegmatite,” Bill said. Here they encountered a shear zone that caused a roof collapse. Wilke abandoned mining efforts around 1922.
Pala International’s mining partner, San Diego Mining Company, reclaimed the tunnel several years ago and began extending it in 2019. “They got to the dangerous area, and then they backed up about 10 meters and went around and hit the pegmatite,” Bill said. “Now they’re in from the front to the back, where we’re hitting tourmaline.”
Carl recalled his initial look at the first new pocket. “Kiel Snyder stopped me and said, ‘Everyone else gave up here,’” he said. “He just believed in it and kept going. Then they hit a small pocket—nothing of note, but something that said, ‘There are stones here.’ I think they called that the ‘Never Give Up’ pocket. Within 10, 15 feet, they hit that first pocket.”
The crystals were large and well formed, and the miners uncovered a very large terminated quartz crystal, a collector specimen. Carl said the crystals in this pocket lack the rubellite color and are not typical of the mine, making them inadequate for cutting and cabbing. But in January of 2023, they discovered a pocket of beautifully colored red rubellite, too included for faceting but suitable for cabbing and carving. “We’re hoping that we’ll hit some more gemmy transparent material,” he said.
“It’s really exciting to have an active mine in Southern California because of its rich history,” Carl said. “At the turn of the century we were hitting a lot, and then it was vacant for so long. So to have some energy coming in with new material is exciting.” @chapter:1


Publication Year: - Title: The Stories Behind the Photos: A Gigantic Aquamarine and ‘Gaudy’ Nature Abstract: The tools of a traveling field photographer include a map, notebook, pen, mobile phone with compass app and a digital camera. Photo by Robert Weldon

Robert Weldon has traveled the world in pursuit of the most fascinating and beautiful gemstones as a gemological photojournalist. He has climbed into mines, trekked miles to the next location and waited patiently for the perfect light. He is as enthralled with the people who mine and deal with gemstones as he is with the places and cultures where they are found.

Weldon has traveled to some of the world’s major gem sites, including Burma, India, East and South Africa, Colombia, Bolivia, Brazil, Russia, and several other gem sources. His photographs are published in scores of international gemological, jewelry and consumer publications, illustrating his own and other authors’ articles, and in several books. They have also appeared regularly on the cover Gems & Gemology since 2008.
Every one of Weldon’s photos has a story to tell  — whether it is how he conceived the image, how he chose to show the gem at its best, or how he decided to show the context of the locality where the gem was found. Over the course of three decades, he has photographed some of the world’s most important gems and jewelry.
He combines art and gemology in a way that makes us even more appreciative of what we see.
“The industry that we are all a part of and love so much is very much a visual one. Everything really relies on our senses, but particularly our eyes and what we see and feel,” he says. “On the basis of a good image we often make decisions in an instant that transfer millions of dollars across the world.”
Here are some of his favorite gem stories.
Don’t Make a Habit of This

The historic Munsteiner aquamarine carving Dom Pedro was donated to the Smithsonian Institution by Jane Mitchell and Jeffery Bland and is housed in the National Museum of Natural History's Janet Annenberg Hooker Hall of Geology. Photo by Robert Weldon
Weldon was given the opportunity to photograph the 10,363 carat (ct) Dom Pedro Aquamarine, a 14-inch tall obelisk carved by master gem sculptor Berndt Munsteiner, at a Tucson show more than 20 years ago.
Unable to fit it into his small portable studio, he and gem dealer Evan Caplan decided to take it out to the desert. They placed it carefully on a rock with the iconic Mission San Xavier del Bac serving as the backdrop. The ancient mission, constructed between 1783 and 1797, juxtaposed against this modern, angular gem sculpture, created a dramatic image.
“Evan crouched inches away, ready to dive for it — and save it — as it swayed slightly in the breeze,” Weldon recalls. They got the shot and spirited the sculpture to safety in Caplan’s booth.
Months later, Munsteiner marched towards Robert, who was “transfixed, mortified and scared” as the legendary carver approached him.
Then he beamed. “Robert, that was a great picture,” he said. After a pause, he added: “By the way Robert, do you know what the value of this stone is?”
Luckily, the photo was a success and was featured in JCK magazine; Munsteiner says a copy hangs in his living room.
“This is something you should never do! It is much too dangerous and too much of a risk,” Weldon says. “Never, never would I do that again.”
The Dom Pedro is “the largest single piece of cut-gem aquamarine” according to the Smithsonian Institute, where it has been on display since 2012. It so breathtaking that the Smithsonian said it is “one of the few objects in the world that can hold its own in a display case just 30 feet from the Hope Diamond.”
A Stunning Stalactite

“Atlantis” Star of the Congo Mine Lubumbashie, Haute-Katanga Democratic Republic of the Congo Approximately 31.75 kg and measures 70 cm in length, by 25 cm in width.   This magnificent specimen of malachite and chrysocolla is from an area in the southern part of the Democratic Republic of the Congo known as the “copper crescent,”  an area famous for its copper mines.    Broken chrysocolla-coated stalactites reveal malachite cores. Look closely; often there is a small hole in the center. These are tubes through which solutions dripped and caused the downward growth of the stalactite. Where these straw-like openings don’t exist, solutions ran down the outside of the stalactite, making them thicker.   Some of the stalactites are oddly curved and bulbous. When stalactites develop they are under the influence of gravity and should form straight growth. The curvature suggests an outside influence like air or water currents caused more growth on one side. All in all, this amazing specimen is reminiscent of a dreamy underwater scene or fantasy world leading to its name, Atlantis. Photo: Robert Weldon
This malachite and chrysocolla specimen, found in a cave in the Congo, weighs 80-90 pounds and is a meter and a half in length.
“Interestingly, it is on display upside down. But we didn’t want to photograph it [or display it] the way it formed in nature, because such positioning would break those beautiful stalactites,” Weldon says.
The GIA Museum acquired this “stunning” malachite and chrysocolla specimen at the 2020 Tucson shows. It has been nicknamed “Atlantis” for its resemblance to the exotic underwater realm. See a video presentation and explanation of its formation.
If you look closely, you may see a small hole in the center of each stalactite. Solutions dripped though these straw-like tubes and caused the downward growth of the stalactite. If a tube opening was not there, the solutions ran down the outside of the stalactite, making them thicker.
Stalactites normally develop under the influence of gravity and should form straight growth. Some of the stalactites in this specimen are oddly curved and bulbous, which suggests an outside influence such as air or water currents that caused more growth on one side.
“You really begin to understand the formation of gemstones just by looking at this. You can see how drip by drip mineral-rich waters gave rise to those colorful stalactites and this is what you see today,” Weldon says. “It is a spectacular display of how only nature can be as gaudy as this. Wow, what a piece — it’s just absolutely stunning.”
Watch a GIA Knowledge Session where Director of the RTL Gemological Library Robert Weldon, Senior Manager of Research Dr. Aaron Palke, and Supervisor of Field Gemology Wim Vertriest offer an exclusive look at GIA field gemology expeditions through previously unpublished photographs. @chapter:22


Publication Year: 2015 Title: Tsavorite Garnet and Mahenge Red Spinel Abstract: Figure 1. Daniel and Andre Assaf of the Tsavorite Factory explained the current market for tsavorite. Photo by Duncan Pay/GIA.

At GJX, Daniel Assaf (The Tsavorite Factory, New York City; figure 1) explained the current market situation for tsavorite garnet, Tanzanian red to pink spinel, and yellow danburite. According to Assaf, the recent recession and the ensuing disruption in supply had less of an impact on his business than increasing demand from China. For him, current rough scarcity and high prices relate more to the growth in the Chinese jewelry market, which 5 to 10 years ago was a fraction of its size today.

Assaf explained that both tsavorite and spinel are rare stones, and even minor changes in the market might have a considerable impact. If just a fraction of one percent of Chinese consumers becomes interested in tsavorite, this has a measurable consequence for supply, especially if production in mining areas is static or even showing slight declines. According to Assaf, the biggest tsavorite purchasers at the source in Arusha, Tanzania, are Sri Lankans buying for the Chinese domestic market. These buyers are prepared to pay very high prices for tsavorite rough.

	The Tsavorite Factory

Daniel Assaf of the Tsavorite Factory provided a detailed market update for tsavorite garnet. In this interview, he explains how unprecedented Asian demand for this rare gem has drastically affected availability and pricing for his customers.
To illustrate the sporadic nature of current supply, Assaf cited a bright, light-toned green grossular garnet. This material has become popular and is sold as “Merelani mint” garnet. It is usually recovered as a byproduct of tanzanite mining. Every so often, he related, miners find a productive pocket and buyers fly in within a couple of weeks.

According to Assaf, the stones on the tray in front of us (figure 2) were from the latest small pocket and had been in the ground just a few months earlier. After the initial flurry of buying activity, Assaf said, it might be another year or two before a similar discovery. In the meantime, the miners might bring buyers the occasional stone—at much higher prices.

Figure 2. These light-toned Tanzanian grossular garnets—termed “Merelani mint”—were mined just a few months prior to the Tucson show. Photo by Duncan Pay/GIA; courtesy of
Tsavorite Factory.
In Assaf’s opinion, today’s tsavorite rough prices in Arusha are almost “out of control.” In effect, there is a disconnect between the Arusha prices and the prices in Tucson, which will likely take several years to readjust.

His company stops buying before the Tucson show because the clientele here will not pay the high asking prices. He cited an instance several weeks earlier in which buyers were offering him top-quality rough for approximately $10,000 per stone, in sizes sufficient to cut 3 ct finished gems. A stone cut from this rough would have a per-carat price well above what the market at the Tucson show would pay. Besides the high asking price, Assaf said there is a significant element of risk in buying rough: “You never know what kind of unpleasant surprises you might find.”

He pointed out that there are places in the world where such high prices are accepted—China and possibly parts of Europe—which is why the few fine rough tsavorites that become available every month are snatched up. Assaf had just heard of a 7-gram piece of tsavorite—perhaps suitable for a 10 ct finished gem—that sold for $200,000 in Arusha.

Assaf showed us two examples of the finest tsavorite colors. In his opinion, both are of equal merit (figure 3, left). Some clients love the deeper, darker color, while others prefer a brighter, lighter-toned green. In either case, he said, the most important consideration is to have a blue color component rather than a yellow one. As long as the gem is not overly dark, and has a bluish cast to the green, it is a quality stone. If it is pale but still has a bluish component to the green, he would classify it as a “mint” garnet.

Figure 3. Left: Some prefer tsavorite garnets with a brighter color, while others prefer a darker appearance. The stone on the left weighs 9.50 ct. Right: This suite of three pear-shaped tsavorites totals 37.79 carats. The approximate asking price for such fine gems would be about $15,000 per carat. Photos by Duncan Pay/GIA; courtesy of Tsavorite Factory.
We asked Assaf how recent Chinese demand has affected tsavorite prices. He said that for sizes under 2 ct, prices have increased as much as 30–40%. The impact has been most dramatic in larger stones: For gems larger than 3 ct, prices have tripled. He felt that prices for large tsavorites have gone up in relation to emerald and other gems due to scarcity of supply and high demand.

To emphasize the point, Assaf chose a suite of three tsavorite pear shapes totaling 37.79 carats (figure 3, right). Each gem was above 10 ct and of the highest clarity, so they constituted exceptionally rare material. Aside from these standouts, Assaf admitted he had few stones of such size—large stones are typically a Tsavorite Factory specialty—due to the prohibitively high price of rough. He lamented that with today’s stratospheric prices, he would have to pay around $200,000 to obtain another 7-gram piece to cut another 10 ct gem. And very few clients—likely none at this show—would accept the resultant high per-carat prices for the finished gem. That leaves two possibilities: Either the prices will adjust in Arusha, or they will become accepted in the U.S.

Assaf recounted that some of the same market factors apply to red spinel. His company does not carry spinel from Myanmar, focusing instead on Tanzanian material. This year, he said, a specific color people were calling “Mahenge”—deep pink with a touch of orange, almost like a “padparadscha” color—was in extremely high demand (figure 4). Assaf had sold all of his “Mahenge” spinel but none of the other colors. While these lavenders, blues, and mauves are quite beautiful and competitively priced at around 10% of the pinks, the red to pink spinels are what his clients seek. Assaf also mentioned that buyers looking for something unusual picked yellow danburite from Tanzania, and that this gem had sold quite well for him at the show (Summer 2008 GNI, pp. 169–171).

Figure 4. An example of “Mahenge” spinel from Tanzania. This was one of the few examples left at Daniel Assaf’s booth at the time of our interview. Photo by Duncan Pay/GIA; courtesy of Tsavorite Factory. @chapter:22


Publication Year: 2022 Title: Aegirine in Poudretteite Abstract: Figure 1. An aegirine crystal inclusion in poudretteite rough from Mogok, viewed with oblique fiber-optic illumination. Photomicrograph by Kyaw Thu; field of view 2.3 mm.
Originally discovered in Canada in the 1960s and named for the family that owned the rock quarry where it was found, extremely rare poudretteite was recognized as a new mineral in 1986. In 2000, the first gem-quality stone was discovered in Mogok, Myanmar. Recently, local miners found a new poudretteite deposit near Pein-Pyit village in the northeastern part of Mogok town. Some of these mined poudretteite gemstones contained unusual green crystal inclusions (figure 1).

Figure 2. Aegirine inclusion showing sprays of acicular crystals in poudretteite rough from Mogok (darkfield and oblique fiber-optic illumination). Photomicrograph by Kyaw Thu; field of view 0.84 mm.
The author examined two rough gem-quality light pink stones weighing about 1.065 and 1.104 ct. Gemological observation and Raman analysis confirmed that the two samples were poudretteite. The green crystal inclusions were present as both single crystals and sprays of acicular crystals in a radial pattern (figure 2). They had a mostly prismatic crystal shape with a bright yellowish green color. Micro-Raman analysis identified them as aegirine, the first discovery of this mineral in poudretteite from Mogok. Aegirine commonly occurs in alkaline igneous rocks, nepheline syenites, carbonatites, and pegmatites. This mineral inclusion could be an indicator of Mogok origin. @chapter:5


Publication Year: - Title: Gemstone ‘Paintings’ Tell Story of a Master Craftsman, Gem and Jewelry Mentor Abstract: Visiting the display window at M.D. Hohenstine Jewelers was a beloved tradition for generations of Columbus, Ohio residents and tourists. When Hohenstine installed his 2,000th display, the mayor declared it M.D. Hohenstine Day in the city. Photo by M.D. Hohenstine/Courtesy of Judith Allen Hall

“For the first Christmas in 50 years, there is no intricate, shimmering picture woven of hundreds of gemstones to decorate the holiday display window of the jewelry store at 37 S. High Street on the ground floor of the Neil House. A tradition that gave a unique flavor to Capitol Square and warmed the hearts of generations of Columbus visitors and shoppers since 1927 has ended with the death of the artisan who painstakingly handcrafted gem paintings for all seasons.” – Columbus Citizen-Journal, 1976 obituary of M.D. Hohenstine

Aside from a few mementos available for sale on Etsy and eBay – a vintage rose gold brooch, a sterling silver spoon, a taxidermy butterfly serving tray – along with a handful of business directory listings and an obituary in the local newspaper, there isn’t much of an online record that tells the story of jeweler M.D. Hohenstine and his Columbus, Ohio retail store.

And yet, Hohenstine’s spectacular window displays, featuring elaborate, artistic arrangements of hundreds of loose gemstones, were a creative and logistical marvel that captured the imagination of Ohio’s capital city for decades.

“People traveled to Columbus from all over and made a point of going to see ‘the window,’” remembers former employee and longtime family friend Judith Allen Hall. “During the Christmas season, people would sometimes line up three and four deep, trying to look in. Over the years, so many feet stood in front of Hohenstine’s store window that the pavement in front of it had to be repaired because of depressions in the concrete.”

M.D. Hohenstine Jewelers’ location on High Street, across from the capitol building in the heart of vibrant downtown Columbus, Ohio, meant that employees had a front-row seat for several important occasions in history for 50 years. Here, a World War II victory parade and United States Army Band performance passes in front of Hohenstine’s store, seen at the far right of the photo. The clock in front of the store was also marked with his name. In 2012, the M.D. Hohenstine clock was refurbished and returned to the store’s first location, at 21 East Gay Street. Photo by the United States Army Signal Corps
M.D. Hohenstine Jewelers sat in the heart of one of the city’s most bustling neighborhoods, where visitors toured, entertainers performed, and politicians and military personnel were welcomed with parades and fanfare. Its location in the historic Neil House hotel – across from the state capitol building, down the street from the iconic Lazarus department store and the city’s theater district – along with its dramatic curved windows and rich, oversized mahogany display cases, drew actors, big-band and jazz musicians, and entertainers, including the apex of jewelry-loving celebrities, Elizabeth Taylor.

“I’m sure whatever design was in the window was what drew her in that day,” says Hall, who notes that “Mr. H,” as employees called him, stayed in the back of the store and let staff have face time with the A-lister as she browsed the counters.

Family members, like Hohenstine’s grandchildren, still look back fondly on their visits to 37 S. High Street. “My favorite memories always included seeing his gemstone displays in the store window,” says Hohenstine’s granddaughter, Tracy Hagen-Smith.

As much as Hohenstine’s intricate displays – all 2,000-plus of them, catalogued diligently in 35-mm slide photographs – drew public attention, he also quietly built a circle of inspiration and influence within the gem and jewelry industry. Hohenstine’s behind-the-scenes mentorship and willingness to pass on his extensive knowledge of gemology, bench jewelry and the logistics of business operations, has continued through generations of GIA-educated jewelers and gemologists long after the doors of his business closed.

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‘Tuesdays Were Display Days’
Gems & Gemology featured Hohenstine’s 1,039th design on its cover in 1951, and noted his “effective window displays,” which started with his collection of hundreds of loose, natural gemstones.

“None were synthetic,” Halls says, “and none were for sale.”

Hohenstine kept the gems he used for his displays in the left drawer of his custom-designed desk, wrapped in papers scrawled with notes like “56 rubies” or “one 10-ct diamond.” He used a soft pencil to sketch designs, often celebrating a season, holiday, local sports team or charity organization, and meticulously arranged the gems over them. Each slide was marked with a number in one corner, and the gems’ identification in the other. The process took at least six hours, and customers walking by could look into Hohenstine’s secure diamond room and watch the craftsman at work.

The gemstone arrangements – unsecured in any way to the plates – were then photographed and carefully carried 100 feet from the diamond room to the window for dressing.

M.D. Hohenstine’s 1,777th gemstone design, seen here both in the window display and close-up, was one of many patriotic designs he created. Right photo by M.D. Hohenstine. Both photos courtesy of Judith Allen Hall
“Tuesdays were display days,” says Hall, who remembers many of the details of how Hohenstine created his window displays. “Every other Tuesday evening, from 1927 until his death in 1976, he trimmed the windows, and a new gem design went in the center of the left window facing the capitol – even on the Hohenstines’ 50th wedding anniversary!”

The slide photographs weren’t simply for posterity. Hohenstine used them as an educational tool for his frequent lectures to gem and mineral societies, as well as civic organizations, such as the Kiwanis Club, for several decades.

M.D. Hohenstine, right, is pictured with son-in-law Stewart Cox at a gem and jewelry lecture to the Euclid, Ohio Kiwanis Club in 1974. Hohenstine, who shared slide photographs of his gem displays to many of his lecture groups as an educational tool, was a believer in gemological and continuing education for everyone. “He was even ahead of his time in supporting a college education for each of his four daughters,” says granddaughter Tracy Hagen-Smith. Photo courtesy of Tracy Hagen-Smith
A Mentor in Jewelry, and Advocate for GIA Education
Hohenstine was born in 1891 and grew up in a relatively poor family in Columbus’ German Village neighborhood; after finishing eighth grade, he helped earn money for the family by working for well-known jeweler and watchmaker Edwin S. Albaugh. Hohenstine married Albaugh’s niece, Margaret Vause, and eventually opened his own small jewelry store in downtown Columbus. Business became so robust that he moved his store to the larger Neil House location in 1927, where it continued to thrive in a competitive area.

He helped differentiate himself early on. “When he learned about GIA courses, which were by mail at the time, he promptly signed up and became an early Certified Gemologist [today’s GIA GG],” Hall says. “He was so proud of that.”

Hohenstine hired Hall’s father, Lawrence Allen, who had also apprenticed under Albaugh and well-known local jeweler, Curly Miller, in 1935. Hohenstine became a friend and mentor to Allen over the next five years, as Allen also began to earn his Certified Gemologist diploma from GIA. Allen left to open his own store, Allen Jewelers, in nearby Mount Vernon, and become vice president of the Ohio Jewelers Association, but the two stayed in touch.

Hall visited Hohenstine’s store with her father as a toddler, and at 12 years old, began to work alongside him at Allen Jewelers in 1948. “I sat next to him every day at the bench,” says Hall, until she started high school.

Lawrence “Larry” Allen, friend and employee of M.D. Hohenstine and father of Judith Hall, became a jeweler who, according to Hall, “could do anything.” Allen was an early student in GIA’s Distance Education courses, and received a glowing, handwritten review on his first exam. “Congratulations – an excellent paper!” wrote GIA’s Bob Crowningshield. “I trust you can complete all courses with a fine record.” Photo courtesy of Judith Allen Hall
Tragedy struck the Allen family shortly after Hall’s graduation in 1954, when her father passed away unexpectedly at 41. Hall, only 19 years old, took the reins of the family store and managed it for a few years until their landlord sold the building and the family shuttered Allen Jewelers permanently.

Hall and her sisters – all trained in the trade – moved to Columbus and joined different jewelry stores. Her father’s old friend M.D. Hohenstine welcomed Hall to his business with open arms. He proudly displayed her Registered Jeweler certificate from the American Gem Society, which she had earned while running the family store, on the wall of M.D. Hohenstine Jewelers – right alongside his own. This was notable, Hall says, as women’s roles as professionals in the gem and jewelry industry were not yet fully accepted in some circles.

She worked alongside Hohenstine for eight years, handling sales, assisting in his window display dressings, and eventually with his encouragement, dipping into the world of gem education. Hall lectured and gave presentations on behalf of M.D. Hohenstine Jewelers until the store was bought in 1966 by fellow jeweler Thomas Hawk. Hohenstine continued to work there, still creating his biweekly gem displays, as Hall moved on to Florida, to teach gemology at multiple schools, including the University of South Florida in Tampa.

Judith Allen Hall, who worked in retail jewelry stores owned by her father, Lawrence Allen, and mentor, M.D. Hohenstine, before embarking on a 30-year career in gemology education, hopes her donation to GIA can help preserve the legacy of jewelers and artists from the past. “There are so many people in the industry who have stories that don’t get told,” she says. “So much of that history could be lost.” Photo courtesy of Judith Allen Hall
A Legacy of Sharing Knowledge
Hall, who took gemology and design classes at GIA through the years, launched into teaching and reached out to her mentor in 1974 with a letter requesting copies of the window design slides.

“At first I asked him because I was trying to fill up 30 hours of class time,” she laughs.

Hohenstine wrote back that he would not send her copies, but originals – though he had previously refused every other request for them from others.

“I am sending 40 slides from my collection as a gift,” he wrote, “with the understanding they are to be used for educational purposes.”

From that point on, Hall never taught a class without them.

“People were always excited to see them,” she says, “and fascinated that someone would have that big of a collection that was not for sale.”

Jeweler M.D. Hohenstine had many creative pursuits outside of jewelry and gemology. “I think of him as always doing, rather than talking,” says his granddaughter, Tracy Hagen-Smith. “His craftsmanship and artistic skills were extensive. He was involved in photography, clock-making, and had his own theater in the basement of his home. I still have two pieces of marquetry that he made in my home.” Here, he plays the organ as his wife, Margaret – “always his biggest fan,” says Hagen-Smith – looks on. Photo courtesy of Judith Allen Hall
Over the next few decades, Hall encouraged her students – many working jewelers and pawnbrokers – to continue their studies at GIA. In a profession like pawn brokerage, she explains, professionals have to make decisions quickly, with nothing more than a loupe in hand and gemological knowledge in their heads.

“I convinced many of them to take GIA classes,” Hall says. “I explained that having that foundation of GIA knowledge is what allowed me to identify gemstones quickly in the first place.”

One of those students, Shane Socash, was a working jeweler looking to expand his gemological knowledge.

“Judith exposed me to the history, lore and beauty of gemstones that I wasn’t getting in other parts of my jewelry education,” says Socash, who went on to earn his Graduate Gemologist diploma and become the owner of David Reynolds Jewelry & Coin in St. Petersburg, Florida. “It allowed me to broaden my knowledge, and I knew since she studied at GIA, that I wanted to explore that direction in my life, too.”

Shane Socash, GG, and owner of David Reynolds Jewelry & Coin, is part of the circle of influence surrounding M.D. Hohenstine, who mentored Socash’s gemology instructor, Judith Hall. As a young jeweler, Socash determined that he wanted to attend GIA like she did, and one day found $400 in the parking lot of a jewelry store. He returned the cash to the owner of the store, but the owner said it wasn’t his and suggested that Socash keep the money if no one claimed it. Socash decided its best use was to put the money toward his first Distance Education course at GIA. Photo courtesy of Shane Socash
When Hall retired from teaching in 2016 at 80 years old, she began to think about the best home for Hohenstine’s slides, including those sent to her by Hawk upon Hohenstine’s passing, and the first edition of Richard T. Liddicoat’s “Gem Identification” book that he gave her.

“In the process of deciding where the best permanent home for them would be, I concluded that GIA is the connecting thread that links us together,” she says. “It’s the vehicle through which and by which we not only receive education, but we also can use to pass on our passion and knowledge of gems and jewelry industry history.”

Hall inquired whether GIA’s Richard T. Liddicoat Gemological Library and Information Center would be interested in a donation to further gemological education. She was “thrilled” when librarians said they would be honored to safeguard the slide collection that Hohenstine had entrusted to her so many years ago.

“For me, that connecting thread was that Mr. Hohenstine, who was an early GIA graduate, taught my father, who also became a GIA graduate,” she says. “My father inspired me to study at GIA, and as a recipient of two generations of jewelry industry education and knowledge, I taught for 30 years and was able to inspire graduates like Shane Socash, who passes on his knowledge to his clients, and even his daughters.”

It’s been just shy of a century since M.D. Hohenstine installed the first of his “handcrafted gem paintings,” and 40 years since he created his last. But because he invested in the next generation of the gem and jewelry industry, his legacy of knowledge, craftsmanship and creative excellence will continue to inspire jewelers in the years ahead – far beyond the borders of the town where he created such unique and memorable art. @chapter:21


Publication Year: 2019 Title: Laboratory-Grown Sapphire with Unusual Features Abstract: Figure 1. This 14.36 ct pink-orange synthetic sapphire contains large fractures with orange staining and some partially crystallized foreign material. Photomicrograph by Moqing Lin; field of view 15.26 mm.

The Hong Kong laboratory recently examined a 14.36 ct pink-orange cushion mixed-cut specimen measuring 12.97 × 11.41 × 10.59 mm. Standard gemological testing yielded an RI of 1.760–1.768, a chromium emission line in red using a handheld spectroscope, strong red fluorescence under long-wave UV, and weak red fluorescence under short-wave UV. These properties were consistent with pink sapphire. Magnification revealed large fractures containing orange staining and some partially crystallized foreign material (figure 1). The foreign material partially crystallized in a dendritic pattern resembling that of diaspore (figure 2). Other natural-looking features included a twinning plane and tubules. Nonetheless, the observation of indistinct Plato lines and a slight curvature in the twinning plane raised suspicion about the stone’s nature.

Figure 2. The foreign material partially crystallized in a dendritic pattern in the fractures, reminiscent of diaspore. Photomicrograph by Moqing Lin; field of view 7.64 mm.

Figure 3. The pink-orange specimen showed a strong red curved band in the DiamondView, confirming its identity as a flame-fusion synthetic sapphire. Image by Moqing Lin.
A strong red curved band observed in the DiamondView confirmed it was a Verneuil (flame-fusion) synthetic sapphire (figure 3). The absence of Ga, V, and Fe in the specimen, determined using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS), provided further evidence supporting its synthetic nature. Ti was below detection limit in all six spots. Cr was below the detection limit in one spot and 37.61–44.31 ppma in five other spots.
Although flame-fusion synthetic sapphires are common in the marketplace, it is unusual to encounter a specimen containing such natural-looking orange staining and partially crystallized foreign material in the fractures. Careful observation as well as advanced testing are required for the correct identification of the natural or synthetic origin of such specimens. @chapter:12


Publication Year: 2018 Title: Designs from Erica Courtney Abstract: Figure 1. Left: Erica Courtney’s Victoria pendant showcases a 114.56 ct colorless topaz with a 2.76 ct Mahenge spinel set above it, surrounded by 86 Mahenge spinels, 20 rubellites, 10 Mandarin garnets, and 558 diamonds. Right: The Autumn pendant contains a 47.16 ct Malaya zircon accented with 3.91 carats of Tanzanian peach spinel, 7.00 carats of peach topaz, 1.31 carats of yellow sapphire, and 1.68 carats of diamond. Photos by Kevin Schumacher.
Erica Courtney has been adorning Hollywood stars for the red carpet for decades. Her eye for color and bringing out a stone’s beauty are immediately apparent. In talking to her at the AGTA show, we discovered that she is the only jeweler in her family. She was introduced to jewelry making at the age of 11 through a Catholic Youth Organization class. This multiple AGTA Spectrum Award winner has always done things her own way, not following trends when choosing stones or creating designs. In fact, she confided that she does not plan what stones she will purchase, but lets the gems pick her. She likened the jewelry design process to a movie going through her head—designs start forming and keep changing until she settles on the final one.

A Closer Look at Erica CourtneyErica Courtney discusses her entry into the jewelry business and her design philosophy, and displays several notable pieces.
Courtney’s work pulls the viewer in to study meticulous details—the more you look, the more you see. Her attention to detail does not stop at the outward-facing front of her pieces. You need to turn the pieces around in all directions to appreciate the designs that spill over the edges and cover the sides and backs of her work. Returning to her point about the gems picking her, she stated that once a gem seduces you, “if you buy for love, you can’t make a mistake.” This is evident in the centerpiece stones in four of her creations. The Victoria pendant (figure 1, left) contains a 114.56 ct colorless topaz accented with a Tanzanian spinel from Mahenge and surrounded by more spinel plus rubellite, Mandarin garnets, and diamonds in an intricate gallery work. In the Autumn pendant (figure 1, right), a 47.16 ct Malaya zircon is surrounded by Tanzanian peach spinel, topaz, yellow sapphire, and diamonds. The Etoile ring’s green African Paraíba-type tourmaline is flanked by blue Brazilian Paraíba tourmalines and diamonds (figure 2, left), while the Imperial earrings (figure 2, right) contain perfectly color-matched Mandarin garnets flanked by pink spinel and diamonds. She confided that the electric orange and pink in the Imperial earrings was her favorite color combination of these four pieces.

Figure 2. Left: Courtney’s Etoile ring has a 7.71 ct Paraíba-type tourmaline accented with 12 Paraíba tourmalines and 370 diamonds, all set in 18K yellow gold. Right: The Imperial earrings feature a pair of Mandarin garnets (21.25 total carat weight) accented with 1.87 carats of pink spinel and 0.71 carats of diamond in 18K yellow gold. Photos by Kevin Schumacher.
Courtney’s desire to understand the entire gem cycle from unmined rough to polished stones set in finished jewelry has taken her backpacking across far-flung locations. She described the experience as giving her an appreciation of how difficult it is to find real gems. She also took notice of the passion of the miners, each wanting to be “the one to have found it.” @chapter:16


Publication Year: - Title: Fall 2009 G&G Book Reviews Abstract: “Famous Diamonds, 5th Ed.”
By Ian Balfour, 335 pp., illus., publ. by Antique Collectors’ Club [www.antique-acc.com], Woodbridge, Suffolk, UK, 2009. $95.00

	“Cameos: Old & New, 4th Ed.”
By Anna M. Miller, edited by Diana Jarrett, 382 pp., illus., publ. by Gemstone Press [www.gemstonepress.com], Woodstock, VT, 2009. $19.99

	“Sapphire Mining in Madagascar”
Contributions to Gemology No. 8, 46 mins., released by GRS Gemresearch Swisslab [www.gemresearch.ch], Lucerne, Switzerland, 2009. $40.00

“Profiting by Design: A Jewelry Maker’s Guide to Business Success”
By Marlene Richey, 135 pp., illus., publ. by MJSA Press [www.mjsa.org], Providence, RI, 2008, $34.95

“Cristalli: L’Ordine dal Caos [Crystals: Order from Chaos]”
By Adalberto Giazotto, Federico Pezzotta, and Giovanni Pratesi, 240 pp., illus., publ. by Giunti Editore [www.giunti.it], Florence, Italy, 2008 [in Italian], 48.00

“Gill’s Historical Index”
By Joseph O. Gill, 647 pp., illus., publ. by the author [www.archive.org, search for “Joseph Gill”], 2009, Free

To view the full section, download the PDF above.

	DATA DEPOSITORY

Famous Diamonds, 5th edition - Additional Material
	Fall, 2009 @chapter:26


Publication Year: 2020 Title: Fluorophlogopite in Burmese Spinel Abstract: Figure 1. This crystal broke the surface of a dark red spinel believed to be from Mogok. It had a lower luster than the spinel, and undercutting indicated a lower hardness. Photomicrograph by Richard W. Hughes, diffuse overhead illumination; field of view 2.5 mm.

Lotus Gemology in Bangkok received a large parcel of dark red spinels for identification. Their colors, inclusion features, and trace element chemistry suggested that they originated from Myanmar’s Mogok Stone Tract.

Figure 2. In darkfield illumination, cleavage was visible inside the crystal. Micro-Raman analysis showed it to be fluorophlogopite. Photomicrograph by Richard W. Hughes, darkfield illumination; field of view 2.5 mm.
In one faceted specimen, a crystal was found breaking the surface (figure 1). The crystal’s surface luster suggested a refractive index below that of the host spinel, and undercutting suggested it was also significantly lower in hardness. The inclusion’s interior also displayed signs of cleavage (figure 2). Thinking it was possibly a carbonate, we proceeded to do micro-Raman analysis on the crystal. To our surprise, the result was fluorophlogopite.
Fluorophlogopite, KMg3(AlSi3O10)(F,OH)2, is a species in the mica group and a member of the trioctahedral mica subgroup. To the best of our knowledge, this is the first reported instance of this species in spinel. Nor are we aware of it having been found included in any gem mineral to date. @chapter:5


Publication Year: 2014 Title: Books: Smithsonian Nature Guide on Gems Abstract: By Ronald Louis Bonewitz, 224 pp., illus., DK Publishing, New York, 2013. $14.95.

              As part of the Smithsonian Nature Guide series, Gems has the look and feel of a field guide or a lab manual. The book is durable enough to serve these purposes, and the technical information contained within lends itself to such use on a limited basis. Although licensed by the Smithsonian Institution and featuring some images from its collection, this book is largely a British product, using terms that are more common among gemologists from the United Kingdom and Europe.

The 34-page introduction serves as an overview of gemology, including such topics as gem formation, classification, cutting, enhancements, synthetics, and history and folklore. The book’s only other section, “Gemstones,” includes segments on precious metals and organics and a glossary, but the largest entry is “Cut Stones.” Here, the various gems are arranged much in the style of a mineralogical text, divided by chemical composition. Sections cover the native elements, sulfides, silicates, and tungstates; based on that system, the cut gems are sometimes are presented out of the order anticipated by someone with a working knowledge of Dana’s System of Mineralogy and Dana’s Textbook of Mineralogy. It should also be noted that the book does not further divide the silicates into categories such as soro-silicates or tekto-silicates. For each featured cut gem, precious metal, and organic gem, there is a profile box detailing its basic properties and, where appropriate, the typical cutting styles. The basic chemical formula is given, along with the name origin, formation and source information, and color images, including examples of rough material.

One of the book’s merits is ease of use, with its portable format and easily located vital information. It contains far more gem materials than most comparable books, opening up a whole new world of gems to the consumer. Another virtue is the profusion of color images used to illustrate various aspects of the gemstones. I applaud the “Gem Enhancement” section: To make an informed purchase, the consumer needs to be aware of methods to improve the appearance, durability, and value of a gem material.

Some areas could use revision. The reader is given no sense of the author’s qualifications to write about gemstones. Another issue concerns the use of the outdated terms “precious” and “semi-precious.” Why should the negative connotation of “semi-precious” be applied to such wonderful gems as alexandrite or red spinel, which often sell for at least as much as those traditionally labeled “precious?” I was surprised that beryl, rather than topaz, was used to illustrate a hardness of 8 on the Mohs scale, and disagreed with the assertion that soft stones are cut only for collectors. This may have been true in the past, but with the recent boom in at-home shopping, softer stones such as fluorite are being purchased by a great many consumers. It is important to inform consumers of the care required for softer gems without chasing them away. The color images, while numerous, do not always convey the actual color of the gem. In many of the photos, lines are used to point out a particular aspect of the gem, such as fire or doubling, yet in some instances you can’t see that feature.

Finally, I found some faulty information. The most conspicuous inaccuracy is the statement that flux-melt gemstones, including some synthetic emeralds, leave curved growth zones. The reality is that curved growth zones are mostly associated with flame-fusion synthetics, which do not include synthetic emerald. Flux-melt synthetic emeralds are known for showing angular growth features. There are other inaccuracies of various degrees that could be addressed, but I do not wish to create too negative an impression.

Despite some outmoded terminology and factual errors, this attractive book’s numerous gemstones, helpful illustrations, portability, and low price make it worth purchasing, especially for the general consumer. @chapter:6


Publication Year: 2017 Title: New Emerald Production from Belmont Abstract: Second-generation stones from Brazil’s Canaan mine are often cleaner and lighter in color than those from the first geological event. Photo by Eric Welch/GIA.

	The Belmont mine in Brazil has been a key emerald supplier in the global market for the past 40 years. It is one of the very few companies that can guarantee a complete mine-to-market chain of custody for the emeralds it produces. As open-pit mining became more expensive over the past decade, underground mining gradually generated a larger share of production at Belmont. Today, all mining activity at the original open pit is underground. Open-pit mining will continue in the two pits to the north of the original site. General manager Marcelo Ribeiro revealed some exciting news about the Canaan mine, about 2 km away from the original pit, and expansion plans for the sorting and cutting facilities.

	Belmont acquired interest in the Canaan mine through a partnership with its original owners. Exploration and underground mining infrastructure are still ongoing at this site. Although the operation just started about a year ago, Ribeiro and his team have learned a lot about this deposit through field studies and chemical analysis. The interesting finding is that there is plenty of beryllium in this area, which makes the survey of chromium concentration critical to locating the mining targets. This is the exact opposite of the situation at the original Belmont site, where beryllium is the critical factor.

	According to Ribeiro, two geological events were responsible for emerald crystallization in the area. The original Belmont mine is mainly influenced by the first event, Canaan by the second. Based on research, the second event was much stronger at the Canaan mine, destroying most of the crystals formed during the first event. The second-generation emeralds have a lower chromium concentration, and therefore lighter green colors, but they are often larger and cleaner than those from the Belmont mine (see above). The new production is sometimes slightly yellowish or bluish. Ribeiro is very excited about the Canaan production, which allows the company to provide a greater selection to its clientele.

	Belmont currently cuts 50% of the Canaan production by value. All medium- to high-quality stones are cut on-site to add more value. To increase the capacity of the operation and make mining cheaper for long-term sustainability, the company plans to add two more optical sorters and further expand the cutting facility. Belmont will also keep promoting its mine-to-market product and better communicate with younger buyers to make them feel proud of their emerald purchases. @chapter:2


Publication Year: 2017 Title: Flashes and Flames inEthiopian Opal Abstract: Figure 1. This 2.68 ct opal displayed play-of-color when viewed face-up (left) and flame-like chatoyancy on its slightly domed base (right). A more pronounced dome might have had the effect of sharpening the sheen into a cat’s eye. Photos by Kevin Schumacher.

	The relatively new source for precious opal located in Ethiopia’s Wollo Province produces material with vibrant play-of-color and occasionally with interesting inclusions. A recently examined 2.68 ct cabochon contained a scattering of octahedral metal sulfide inclusions (relatively common in Ethiopian opal) along with an unusual combination of optical phenomena: play-of-color and chatoyancy. Face-up, the stone showed the typical flashes of colors one would expect in precious opal (figure 1, left). However, the back of this cabochon contained an interesting structure that produced a sheen-like chatoyancy over its slightly rounded surface (figure 1, right). This chatoyant zone was strikingly similar to the flame structure seen in some non-nacreous pearls, which is produced by an intricate structure of aragonite crystal laths (figure 2). In the case of this opal, the flame-like structure’s cause remains an enigma, though it could be due to the structural influence of a preexisting fibrous mineral replaced by opal. Unfortunately, Raman analysis was unable to detect any presence of another mineral phase in the chatoyant area, so the exact cause of chatoyancy is still unknown.

	Figure 2. The fibrous nature of the opal’s unusual chatoyant zone is clearly revealed, along with the numerous minute octahedral black metal sulfide crystals that are a common inclusion in opal from Wollo. Oblique fiber-optic illumination. Photomicrograph by Nathan Renfro; field of view 2.73 mm.

	Chatoyancy is not unheard of in opal, though it is quite rare in precious material. Cat’s-eye common opal from Tanzania owes its optical effect to arrays of parallel needles, while the asterism and chatoyancy unique to the precious opal of Spencer, Idaho, are due to the arrangement of the same silica micro-spherules responsible for its play-of-color. At least one cat’s-eye precious opal was observed to even “wink” at the viewer when viewed with opposing lighting (Summer 2003 Lab Notes, p. 148). This Ethiopian opal cabochon joins the rarefied group of chatoyant precious opal with its unusual phenomenal display of flashes and flames. @chapter:39


Publication Year: 2024 Title: The jewelry industry's use of recycled resources Abstract: Pandora, the world's largest jewelry retailer known for selling bracelets and silver charms, has sold more than 100 million pieces of jewelry per year. The Danish company has factories in Thailand and employs over 12,200 craftsmen in Thailand. Pandora has announced that it exclusively uses recycled metals, including silver and gold, without using newly mined minerals.

Pandora's initiatives mark significant steps for a large company in reducing its environmental footprint, which is a measure indicating how much burden the production process imposes on the environment. Alexander Lacik, Pandora's CEO, stated in an interview that the company aims to lead in using recycled metals as an example for the market. If Pandora can create change by using recycled silver and gold in jewelry production, it means that others can follow suit.

Pandora refrains from mining new metal ores but utilizes metals that have already been mined, significantly reducing greenhouse gas emissions. Mining requires more energy and resources compared to recycling and contributes to pollution from substances like cyanide. According to the World Gold Council, recycling gold reduces greenhouse gas emissions by over 99% compared to mining new gold, while silver recycling reduces carbon emissions by over 66% compared to mining new silver.

Other brands like Prada and Monica Vinader have also started using recycled metals. However, industry observers have warned that recycled metals may create an image of reducing environmental impact more than it actually does. This is because each person interprets the term "recycled" differently, similar to how "sustainability" can have varying meanings.

Ms. Tiffany Stevens, CEO of the Jewelers Vigilance Committee based in New York City, which specializes in ethics and public policy advocacy in the jewelry industry, stated that the term "recycled" generally carries a positive connotation, making jewelry made from recycled materials appear environmentally friendly. However, interpreting the meaning of "recycled" remains problematic, especially when the source of recycled metals is not specified. This is one reason why Ms. Stevens has requested the Federal Trade Commission to prohibit the use of the term "recycled" for jewelry sold in the United States. She expects the Federal Trade Commission to announce environmental marketing guidelines within the year 2023.

Currently, this policy dictates that using the term "recycled" without using or transforming materials from waste is considered deceptive. Generally, metals are not considered waste because when melted down, they can be reused for many centuries while retaining their original value. Additionally, "recycled" does not prompt consumers to consider the source of metals as they should, as some metals may come from mines supporting child labor or criminal networks. Mr. Patrick Schein, owner of a mining company and committee member of the Alliance For Responsible Mining, an organization advocating environmentally sustainable mining, stated that the term "recycled" has turned metals sourced from unethical practices into seemingly ethically transformed new metals.

While the Alliance For Responsible Mining has been supporting the development of responsible supply chains in the jewelry and gemstone industry through working with small-scale mines to increase environmentally responsible mining practices, their 2023 report and partners have pointed out that recycled gold has created precarious situations for workers. For example, there are issues with obtaining official mining permits and working in remote locations.

Mr. Lacik stated that while Pandora has shifted to using recycled metals to reduce environmental impact, there is a need to decide whether climate issues are more or less significant than social issues for any group. For Pandora, addressing climate issues is a paramount concern for humanity in the long term.

Despite Pandora's shift to using recycled metals to reduce environmental impact, statistical data shows that gold and silver mining has not slowed down in the past decade. Therefore, the adoption of recycled metals by various companies may only marginally reduce environmental impact.

More than 100 employees of Pandora have been involved in the shift to using recycled metals. In 2024, they transitioned from mining to cultivating lab-grown diamonds. This change in metal sourcing has led the Responsible Jewellery Council, a global leader in setting standards for jewelry and gemstone production based in London, to adjust their processes and tools for measuring diamond standards.

MKS PAMP, a Swiss trading and mining company and a partner of Pandora, mentioned that they can trace the origin of every gram of recycled metal to its owner. Xavier Miserez, the head of sales, commented that the company avoids using recycled metals from sources that do not treat their employees ethically.

Pandora plans to invest over 10 million US dollars per year in transitioning to recycled metals instead of newly mined metals. The company is prepared to bear these costs. However, Lacik believes that factors influencing consumer purchases are design, price, and some groups may prioritize sustainable production, although they may not be the majority.

Besides the design and pricing of jewelry and pearls being the main factors in consumer decision-making, environmental awareness is also growing. The world's largest pearl producers have started using recycled metals in pearl production instead of mining new ones from underground, aiming to reduce environmental footprints and address climate change issues. Therefore, Thai entrepreneurs and exporters may study and improve the jewelry and pearl production supply chain with a greater focus on the environment, while keeping up with the updates in environmental marketing practices (Green Guides) by the Federal Trade Commission, to align marketing strategies in the United States with the guidelines set by the FTC @chapter:33


Publication Year: 2019 Title: Ponderosa Sunstone Update Abstract: Two Oregon sunstones weighing 7.07 and 2.48 ct. The stone on the right, faceted by Larry Woods, has a very rare deep red color. Photo by Robert Weldon/GIA, courtesy of John Woodmark, Desert Sun Mining.

John Woodmark, president of Desert Sun Mining and Gems (Depoe Bay, Oregon), updated us on the Ponderosa mine, which he calls the most productive source of Oregon sunstone (see above). Demand has increased annually over their 17 years of production, he said. With the larger excavator and high-capacity screen they brought on in 2015, they now mine about 4,300 kg (4.8 tons) of sunstone rough per year, up from about 2,000 kg (2.2 tons) in 2014. About 3% of this material is facet grade. Ponderosa now produces 4,000 to 5,000 cubic yards of concentrate in seven days—more than enough to process in one season (which only lasts five or six months due to snow at the high elevation). Desert Sun was once limited to mining at about 50 feet deep, but the excavator has allowed them to go a few hundred feet deep into the source. Woodmark said the sunstones at that depth are larger and less fractured, and there are some excellent red stones of good size.
Woodmark said demand is especially strong from American and European customers age 45 and under because they want natural, untreated gemstones such as sunstone, opal, and jade. They also love Oregon sunstone’s schiller effect, a sparkle caused by reflective copper platelets that makes the stone “different from what their friends have.” Desert Sun will be using social media this year for the first time to reach customers looking for unique gemstones.
Jewelers are excited about Oregon sunstone because of the potential high markup, according to Woodmark. He noted that sunstone isn’t competing with diamond, ruby, sapphire, and emerald, for which a jeweler might see a 10% or 15% profit margin. Oregon sunstone can yield a triple or quadruple markup, yet it is still relatively affordable: Woodmark said the yellow sunstones sell for about $30 per carat while the reds can go for $300 to $4,000 per carat. Sunstone’s affordability, profit margin, and appeal to young consumers make it attractive to jewelers.

	John Woodmark updates us on the Ponderosa mine and the sunstone market.

Woodmark said the jewelry industry’s demand for calibrated sunstones continues to grow, and Desert Sun now receives significant orders from large companies. A typical order might be a thousand 5 mm rounds of orange sunstone. Every color sells well, he told us, but it is difficult to get a specific band of color in natural, untreated gemstones, so they are trying to grade more consistently. Desert Sun has seven colors, each graded with and without schiller, so overall there are 14. He tries to educate jewelers, manufacturers, and designers on the fact that color in natural stones is more variable—and that many have unique color—to encourage them to use more than one color in their pieces.
Woodmark sees a bright future for Oregon sunstone as more consumers become aware of it. He acknowledged that there will come a time when he and Bruce Moore, Desert Sun’s executive vice president, will have to step away from the deposit. “We’re barely scratching the surface of what people could do with this mine,” he said. Desert Sun only exhibits at the AGTA show in Tucson, but Woodmark said if someone were to take over the mine, they could do 10 shows a year across the United States. At that point, he said, sunstone would “take off.”

	Sonja Kreis describes an Oregon sunstone and gold nugget piece by Kreis Jewellery. @chapter:7


Publication Year: 2010 Title: X-ray Computed Microtomography: Distinguishing Natural Pearls from Beaded and Non-Beaded Cultured Pearls Abstract: The distinction of natural from cultured pearls traditionally has been based on X-radiography. X-ray computed microtomography (μ-CT) has recently been applied to gain more insight into pearl structures. Using this technique, this article presents features observed in a selection of natural pearls and beaded and non-beaded cultured pearls. Based on these observations, μ-CT is shown to be a powerful tool for pearl identification.

	DATA DEPOSITORY

	Supplementary Videos (see below)
	Summer, 2010

	Figures 1a and 1bTwo Natural Pearls

	Two natural pearls, samples mxt 3 (freshwater; a) and mxt9 (saltwater; b); for details and explanation, see table 1 and figure 3.

	Figure 2A Beaded Cultured Pearl

	A beaded cultured pearl, sample mxt 14b (saltwater); for details and explanation, see table 1 and figure 4.

	Figures 3a, 3b and 3cTwo Non-beaded Cultured Pearls

	Two non-beaded cultured pearls, samples mxt 1 (freshwater; a) and mxt 61_14 (saltwater; b). Also included is a short movie showing the rendered model of the cavity structure (“moustache”) in the center of sample mxt 1 (c); for details and explanation, see table 1 and figures 5 and 6.

	Figure 4A Non-beaded Cultured Pearl

	A non-beaded cultured pearl with a complex structure, sample mxt 21_1 (saltwater); for details and explanation, see table 1 and figure 8. @chapter:14


Publication Year: 2023 Title: Ruby with Interesting Synthetic Overgrowth Abstract: A large cavity partially filled with synthetic overgrowth on the pavilion of a heated Burmese ruby in darkfield lighting (left) and reflected lighting (right). Photomicrographs by Nicole Ahline; field of view 7.19 mm.
The Carlsbad laboratory received a 3.02 ct ruby for a colored stone identification and origin report. Standard gemological testing was consistent with ruby: a hydrostatic specific gravity of 3.96 and a ruby spectrum in a handheld spectroscope. Internally, the stone displayed white flakes in a hexagonal formation and roiled graining. Partially healed fissures with residue, which result from heating in the presence of a flux, were also documented. The inclusion scene, along with the stone’s trace element chemistry collected using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS), were consistent with Burmese ruby. This ruby was not treated by beryllium diffusion, as no beryllium was detected by LA-ICP-MS. The curious feature of this stone was a large cavity on the pavilion that was partially filled with synthetic overgrowth that was observed in the microscope (see above).
Synthetic overgrowth can be a byproduct of heating a piece of corundum at high temperatures, with or without the presence of a flux. This creates an environment in the crucible that allows for the partial dissolution of corundum and can result in synthetic corundum overgrowth on the surface and in cavities of the heated stone. Synthetic overgrowth is typically an aggregated structure of hexagonally shaped, platy crystals (Fall 2002 G&G Lab Notes, pp. 255–256). When viewed in reflective lighting, there is no luster difference between the host corundum and the synthetic overgrowth, as the two materials have the same refractive index. The gaps that could be observed between the crystals in this stone showed how they grew in different orientations.
Synthetic overgrowth is common enough that it should always be looked for in corundum that has undergone high-temperature heat treatment. There are cases where synthetic overgrowth can be observed using polarized light, but careful analysis is required because the overgrowth can completely fill cavities and be inconspicuous. @chapter:19


Publication Year: 1983 Title: A Computer Program for Gem Identification Abstract: Following a feasibility study of computer-aided gem testing, which resulted in a student-level gem identification program, the author has developed a professional version containing data on over 200 gem materials and gem simulants. The program sections include Gem Identification (using test inputs for R.1, values, optic sign, S.G., etc.), Gem Data Tables (arranged in alphabetical, R.I., and S.G. order), Gem Data Comparisons, Gem Data Pages, and Gem Calculations (for determinations of S.G., reflectivity, critical angle, and Brewster angle). This type of computer program provides rapid access to gem constants and characteristics, and can assist the less experienced gemologist by identifying unfamiliar or rare stones and indicating the various alternatives. @chapter:23


Publication Year: 2022 Title: Fall 2022 Auction Highlights Abstract: Figure 1. The 11.15 ct Williamson Pink Star is set in an 18K pink and white gold ring, along with 1.41 carats of trapeze-cut diamonds and 0.14 carats of brilliant-cut pink diamonds. Courtesy of Sotheby’s.
The astounding results of colored diamond sales in the spring auction season (Summer 2022 GNI, pp. 260–263) left expectations high for fall. Pink diamonds set the scene for the beginning of the season, starting with a bang at a Sotheby’s stand-alone sale in Hong Kong in October. Selling for $57.7 million, almost three times its estimate, the 11.15 ct Williamson Pink Star (figure 1) became the second most valuable jewel ever sold at auction. After 20 minutes and 50 bids, the GIA-graded natural Fancy Vivid pink internally flawless cushion-shaped diamond broke the record price per carat for any diamond or gemstone sold at auction, at $5.2 million a carat.

Figure 2. The 18.18 ct Fortune Pink sold in Geneva for $28.9 million. Courtesy of Christie’s.
The colored diamond trend headed downward the following month with the Fortune Pink (figure 2) at Christie’s Magnificent Jewels sale in Geneva, selling below expectations at the lower end of its estimate. Fetching $28.9 million, the GIA-graded 18.18 ct stone is the largest pear-shaped Fancy Vivid pink diamond ever sold at auction.

Figure 3. Surrounded by pink diamonds, this 31.62 ct Fancy blue diamond pendant sold within its estimate at $11.8 million. Courtesy of Christie’s.
Another pink diamond, a 13.15 ct emerald cut, was slated to lead Christie’s December Magnificent Jewels sale in New York before it was withdrawn weeks before the auction and later revealed as alleged stolen property. A 31.62 ct Fancy blue diamond pendant (figure 3) was then placed as the top lot of the auction. The GIA-graded pear modified brilliant cut, noted by Christie’s as the largest of its kind to appear at auction, garnered $11.8 million, toward the lower end of the estimate. Three other blue diamonds offered by Sotheby’s from the De Beers Exceptional Blue collection drew lackluster results throughout the season. Two were left unsold, and one was withdrawn prior to auction.

Figure 4. The 303.10 ct Golden Canary, recently recut from the Incomparable, became the third most valuable diamond sold at auction. Courtesy of Sotheby’s.
In an unexpected conclusion to the season, the Golden Canary (figure 4) sold below its estimate at $12 million. Without a reserve, Sotheby’s anticipated the 303.10 ct pear-shaped Fancy Deep brownish yellow diamond to secure more than $15 million in the New York auction. Still, the diamond became the third most valuable diamond ever sold at auction, Sotheby’s noted. As the largest flawless or internally flawless and largest pear-shaped diamond graded by GIA to date, the Golden Canary can be traced back to a young girl’s discovery of an 890 ct rough near her uncle’s house in the Democratic Republic of the Congo in the early 1980s. The 407.48 ct Incomparable, the largest of the 15 finished stones from the rough diamond, was recently transformed into the Golden Canary to improve its color and shape.
The real surprise of Sotheby’s New York auction—and perhaps the season—was the sale of a ring featuring a 6.25 ct emerald recovered from the legendary 1622 shipwreck of the Nuestra Señora de Atocha. The ring sold in just five minutes for $1.2 million, more than 17 times its estimate. All proceeds were donated to humanitarian efforts in Ukraine. @chapter:30


Publication Year: 2019 Title: Quarterly Crystal: “Ball Bearing” in Quartz Abstract: Figure 1. This doubly terminated scepter quartz crystal from Sichuan, China, weighs 200.28 ct and measures 75.03 mm in length. Photo by Diego Sanchez.
Quartz crystals with three-phase fluid inclusions from the Jinkouhe mine in the Sichuan Province of China have been sold for many years at gem and mineral shows such as those held annually in Tucson, Arizona. Unfortunately, many of those crystals are damaged due to the mining methods used and the packing together of numerous crystals for transport. Good terminations on those crystals are few and far between, and the edges are generally chipped, while the broad flat crystal faces are often scratched and abraded.
So it was with high interest that we examined the relatively large doubly terminated scepter rock crystal quartz shown in figure 1. At 200.28 ct and measuring 75.03 × 21.76 × 17.98, this crystal was much larger than most others from the Jinkouhe mine. It was preserved in its own cotton-lined box, and as shown in figure 1, essentially undamaged.

Figure 2. Nomarski differential interference contrast revealed light etching on the prism faces of the quartz crystal. Photomicrograph by Nathan Renfro; field of view 0.72 mm.

Figure 3. In this image, the silver-gray bubble can be seen at the right side of the liquid-filled void. The coating gives it the appearance of a small ball bearing. Photomicrograph by Nathan Renfro; field of view 7.42 mm.

Figure 4. The metallic-looking bubble has floated toward the left end of the fluid inclusion chamber. Photomicrograph by Nathan Renfro; field of view 7.42 mm.
Microscopic examination of the crystal revealed light etching on the prism faces (figure 2), which was highlighted using Nomarski differential interference contrast. Internally there were several primary fluid inclusions, with typical black organic compounds as the solid phase. One fluid inclusion in particular contained a gas bubble (figure 3) that moved freely across the entire length of the void (figure 4). The bubble was coated with a metallic-looking substance that gave it the appearance of a small stainless steel ball bearing. We could not identify the coating but suspect that it was an organic compound. @chapter:13


Publication Year: - Title: Ruby Journey Abstract: Few people outside the gem industry realize the true nature of a gemstone’s journey from the mine to the counter of a store. Whether the gem is being offered to consumer’s at a traditional jewelry store’s counter, an internet shopping site, or a television broadcast the journey always involves a great deal of effort.  Tons of earth and countless hours of labor are needed to being a gem from mine to market. @chapter:28


Publication Year: 1989 Title: Beryl Gem Nodules from the Bananal Mine, Minas Gerais, Brazil Abstract: Bicolored (aquamarine-morganite) beryl from a 1986 discovery at the Bananal mine is described. Most of the cutting material was of carving grade, but a small percentage of the crystals contained faceting-quality morganite gem nodules. This is the first published report of gem nodules of a species outside the tourmaline group. Much of the Bananal morganite is of a pleasing orange to pink-orange color that changes to pink on extended exposure to heat or sunlight. The inclusions in the nodules appear to be limited to muscovite crystals, while the rest of the material (both aquamarine and morganite) contains two- and three-phase inclusions, but little or no muscovite. The cause of the gem nodules is not established, but it may relate to the presence of the same type of variation in mosaic texture observed in some color-zoned tourmaline crystals. @chapter:3


Publication Year: 1982 Title: The Natural Formation and Occurrence of Green Quartz Abstract: Amethyst may develop into the more common citrine and rarer green quartz naturally under certain geologic conditions. On the California-Nevada border, just north of Reno, amethyst, citrine, and green quartz do occur together in clusters of crystals in detritus. These crystals, found lying loose in rocky and sandy rubble, appear to have eroded from cavities and vesicles in the inaccessible cliffs above. The quartz was deposited in these spaces by the slow accumulation of silica from migrating solutions. Low-grade radiation over a geologic time span was responsible for the alteration of the ferric and ferrous quartz into its amethystine color. Secondary, high-temperature, extruding volcanic bodies are believed to be responsible for the subsequent color change to citrine or green quartz. @chapter:4


Publication Year: 1987 Title: The Occurrence and Gemological Properties of Wessels Mine Sugilite Abstract: Examination of jewelry-quality sugilite shows that it consists of manganese-bearing sugilite and other minerals in a polycrystalline aggregate. The material occurs in a large stratiform manganese orebody at the Wessels mine near Kuruman, South Africa. Some 12 to 15 tons of sugilite of varying quality are estimated to occur at the mine. The attractive purple color is due to the presence of about 1-3 wt. % manganese oxide. The research reported here revealed that there are actually two types of gem materials that have heretofore been called sugilite: one that is predominantly manganoan sugilite with minor impurity minerals, and the other that is chalcedony mixed with (and colored by) sugilite. @chapter:0


Publication Year: 2020 Title: Clarity-Enhanced Glass Imitating Emerald Abstract: Figure 1. Round gas bubbles in host material and flat gas bubbles within the break of fractures. Photomicrograph by Michaela Stephan; field of view 1.99 mm.

The Carlsbad lab received a transparent green octagonal step cut for identification. This stone visually resembled emerald due to its rich green color and large fractures. However, its single refractive index of 1.510 was not consistent with emerald’s double refractive index of 1.577 to 1.583.
Examination with a standard gemological microscope revealed no natural inclusions. Instead, it showed rounded gas bubbles in the body as well as flattened gas bubbles in surface-reaching fractures (figure 1). This stone has also been examined with FTIR and long-wave UV. When observed with long-wave UV, the fractures emitted a weak white fluorescence while the body of the stone showed a very weak blue fluorescence. The presence of these features was enough to conclude it had been clarity enhanced.

Figure 2. Shown are the infrared spectrum for the octagonal step cut (red line) and the typical reference spectrum for manufactured glass (dotted black line). The spectra have been offset for clarity.
Additionally, rounded gas bubbles separate from fractures, an RI of 1.51, and the sample’s FTIR spectrum (figure 2) were consistent with manufactured glass.
These gemological properties and observations identified the material as clarity-enhanced manufactured glass. Due to emerald’s high value, it is common for imitations to show up in the market. Items such as this demonstrate the need to always be cautious when purchasing gemstones. @chapter:12


Publication Year: 2020 Title: Bicolor Synthetic Sapphire Abstract: Figure 1. Split boules of bicolor synthetic sapphire grown by flame fusion. Photo by Jennifer Stone-Sundberg; courtesy of RusGems.
At the JOGS show, a wide selection of synthetic gem materials was offered by the Bangkok office of RusGems, a synthetic crystal growth company out of Russia. Olga Tanskaia showed us their extensive color range of synthetic sapphire, spinel, beryl, garnet, and other lab-grown crystals produced using a variety of crystal growth methods. She noted that blue and red synthetic gems are always their best sellers.

Figure 2. Left: Bicolor 14.83 ct synthetic sapphire showing popular teal blue and purple colors. Photo by Kevin Schumacher; courtesy of RusGems. Right: Wisps of presumably CoAl2O4 at the boundary of the teal and purple colors in the crystal. Photomicrograph by Nathan Renfro; field of view 7.05 mm.
As we found with natural sapphire this year, bicolor synthetic sapphire, both rough and cut, was also available and popular (figure 1). This material is grown by flame fusion, and the chromophore component of the powder composition is altered during the growth process at the desired length. Many different color combinations were available, including some with the popular teal blue and purple hues (figure 2, left). The inspiration for applying this method of color zoning to these flame-fusion grown crystals came from historical work on synthetic ruby laser rods where colorless (or “undoped”) regions were desired for the ends of the rods (figure 3). A process to grow a single crystal having pure aluminum oxide for a certain length, then adding the desired level of chromium to the growth for the laser rod portion of the length, and then returning to pure aluminum oxide was developed to achieve this.

Figure 3. Synthetic ruby rod grown by the flame-fusion technique showing chromium-free ends. Photo by Jennifer Stone-Sundberg; courtesy of RusGems.
We took the step-cut bicolor synthetic sapphire in figure 51 back to the GIA lab to determine the trace element chemistry responsible for generating the teal and purple hues. Using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS), we found that the teal end contained no Be, Mg, Ti, V, Mn, Fe, or Ni but did contain small amounts of Cr and Ga (approximately 4 ppma and 0.5 ppma, respectively) and a substantial amount of Co (approximately 140 ppma). The purple end similarly contained no Be, Mg, V, Mn, Fe, or Ni but did contain small amounts of Ti (0.6 ppma) and Ga (0.4 ppma), with substantial amounts of Co (120 ppma), and Cr (470 ppma). Cobalt is giving this crystal the greenish blue component of its color, and chromium is modifying the hue to purple. We used UV-Vis spectroscopy to detect absorption peaks that could be used with the trace element chemistry to explain the two differently colored regions. We identified chromium peaks at approximately 400 and 560 nm responsible for the red color component in the purple half. We also identified an additional peak in the purple half at around 640 nm, likely due to Co3+. In the teal half, we did not find the Cr3+ peaks but did identify Co3+ peaks at 640 nm and at around 440 nm, and a peak around 600 nm due to Co2+ (K. Schmetzer and A. Peretti, “Characterization of a group of experimental Russian hydrothermal synthetic sapphires,” Journal of Gemmology, Vol. 27, No. 1, 2000, pp. 1–7).
In inspecting the inclusions at the boundary between the two differently colored portions, we discovered bright blue wisps of what we believe to be CoAl2O4 (figure 2, right), a spinel-structure material referred to as “cobalt blue” that is used to impart a blue color to glass, ceramics, and plastics.
The ability to generate just about any hue in sapphire, including color zoning, was readily apparent when looking through the offerings of RusGems. It was fascinating to see evidence of the direct influence of the high-tech laser industry on these synthetic gems. @chapter:12


Publication Year: - Title: GIA Field Gemologists Seek Ruby in Mogok, Myanmar Abstract: Searching for Ruby in Mogok

	Join GIA field gemologists in a search for ruby in Mogok, Myanmar.

	Venture into Myanmar’s Mogok mining area and its bustling gem markets with GIA Field Gemologists Vincent Pardieu and Andy Lucas, who traveled to this legendary location in January and February of 2014 with videographer Didier Gruel.

	This video focuses on ruby, Mogok’s most iconic gem. Mogok has an unparalleled reputation as the source of fine rubies that goes back more than 800 years. Rubies are mined either from the gravels of secondary deposits or deep underground from primary deposits in marble.

	The Mogok mining area is about 400 miles (650 km) north of Yangon in a densely vegetated, mountainous area rising to 7,700 feet (2,347 meters) above sea level.

	At most mines, you’ll find Kanase women searching through the white marble tailings for traces of the area’s fabled rubies, the surroundings ringing with the impact of their hammers. By local tradition, they have the right to keep the gemstones they find. These women can also be seen selling their finds at the open gem markets.

	While there, Pardieu negotiated with them for gemological samples—the rubies and spinels often found in the marble host rock. “The only better solution would be for us to go down into the mine and find the samples ourselves,” says Pardieu, looking at pieces the women offered him, “but you could spend hours and hours hammering the marble to collect that—this is really good.”

	In the video, you’ll also venture into the depths of Mogok’s underground mines, some of which are more than 980 feet (300 meters) deep, requiring long, tricky descents. The difficult access hints at the effort the miners must make day after day to reach ruby-bearing rock. “Now we start to understand the value of rubies,” explains Pardieu. Uncovering ruby requires stamina and faith, he says. “It’s a lot of hard work and it’s a lot of hope from the miners—it’s a mix of hope and hard work.”

	These GIA Field Expeditions (FE49 and FE50) took place in February 2014. @chapter:25


Publication Year: 1982 Title: Winter 1982 G&G Lab Notes Abstract: "Chameleon" Diamond
Crusader Diamond
Diamond Oddities
Unusual Absorption Spectrum in Diamond
Emerald
Parisite
Plugged Natural Blister Pearls
Star Quartz
Heat Treated Sapphire
Spinel and Sapphire, Colored by Cobalt
Star Spinel
Unclassified Oddities

To view the full section, download the PDF above. @chapter:32


Publication Year: 2023 Title: The history of gemstones in Chanthaburi_28 Abstract: Ruby, a rare and highly prized gemstone, is renowned for its red color and popularity in the market. Siamese rubies were once mined from four mines in Chanthaburi and Trat provinces: Nong Bon, Na Wong, Tok Phrom, and Rai. Rubies from each of these mines, when subjected to heat treatment or burning, exhibit varying shades of red such as pinkish-red, pigeon's blood red, or deep red almost approaching black, commanding the highest prices among ruby varieties. @chapter:25


Publication Year: 2016 Title: A Halo in a Sri Lankan Taaffeite Abstract: Figure 1. This 0.57 ct taaffeite from Sri Lanka measures 5.63 × 4.00 × 3.21 mm. Photo by Elise A. Skalwold.

	The lovely chromium-bearing purplish red taaffeite from Sri Lanka seen in figure 1 is home to a swarm of included crystals, but one is particularly intriguing. Due to this crystal’s depth and minute size, it cannot be conclusively identified without destructive testing. But its opaque black appearance leads us to believe it is either thorianite or uraninite. The latter is a uranium-rich mineral formerly known as pitchblende and reported to exist in taaffeites from this locality (see E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Volume 3, Opinio Verlag, Basel, Switzerland, 2008, pp. 649–650).

	The strong alpha emissions from such mineral inclusions may lead to stress fractures in the host mineral. Unlike gamma and beta particles, alpha particles are massive and can cause considerable destruction in their path. In this case, it appears the gem has escaped fracturing: the effect is manifested as a concentric two-tiered halo surrounding the black crystal (figure 2). Its three-dimensional bulge-like appearance may be interpreted as radiation-induced distortions in the taaffeite’s crystal structure. These distortions also locally changed the taaffeite’s color, transparency, and refractive index and resulted in other strain features.

Figure 2. In the taaffeite, a radiation-induced two-tiered halo surrounds a minute black crystal; the outer tier is subtle. The haloed crystal is most likely thorianite or uraninite, while numerous colorless zircon and apatite crystals are also present. Photomicrograph by John Koivula; field of view 0.75 mm.

	While the colorless inclusions display reflective surfaces in oblique light from the right, the haloed black inclusion does not. Instead there is a reflection-like scattering of light from the halo surrounding it. We suggest that this is due to a gradational difference in the taaffeite host’s refractive index farther from the black crystal as light is scattered off of the disrupted region. An everyday example of this comes from observing the sun before it rises above the horizon, an optical phenomenon that would not occur without the gradational refractive index of the atmosphere bending the light. The refractive index of the atmosphere decreases with altitude. Because light rays are bent toward the higher refractive index, we may surmise that the inclusion’s halo has a lower refractive index than the rest of the taaffeite host. To support this explanation, in-depth exploration of the geometry of the halo’s refractive index will be needed.

	In the early days of radioactivity studies by scientists such as G.H. Henderson (in a series of five papers published between 1934 and 1939), these inclusions were known as “pleochroic halos.” Although this term may be misleading, the halos’ appearance is partially the result of localized changes in optical properties in the vicinity of the inclusion. Such inclusions are also relevant in determining the age of the planet by studying the characteristics and effects of radioactive guests in various minerals. @chapter:4


Publication Year: 2014 Title: Mixed-Type Cape Diamond Abstract: Figure 1. This 2.16 ct Fancy orangy yellow diamond is a mixed-type IaA>B. Photo by Jian Xin (Jae) Liao.

Natural yellow type Ia or “cape” diamonds, the most common of all colored diamonds, are identified by the N3 (415 nm) and N2 (478 nm) absorption lines in the UV-visible range. These defects produce the characteristic yellow hue, and the N3 line produces the blue luminescence, so often observed in these stones. Weaker bands at 452 and 465 nm may also be visible (C.M. Breeding and J.E. Shigley, “The ‘type’ classification system of diamonds and its importance in gemology,” Summer 2009 G&G, pp. 96–111).

The New York laboratory recently examined a 2.16 ct Fancy orangy yellow diamond (figure 1) with unusual features for a cape stone. When analyzed with a UV-Vis spectrometer, it exhibited a cape spectrum and an unexpected 480 nm band, a defect usually associated with orange color (figure 2). Infrared spectrometry revealed a well-defined IaAB diamond, as opposed to the saturated Ia spectrum typically associated with cape diamonds. These abnormal features prompted further testing, and the DiamondView revealed zoned blue and yellow fluorescence (figure 3). Raman spectroscopy of the transparent, elongated crystal within the diamond, visible in the DiamondView, identified it as a colorless garnet, a common inclusion in cape diamonds.

Figure 2. UV-visible spectrum displaying “mixed” cape (red) with overlay of “normal” cape (blue).

Figure 3. The cape diamond’s DiamondView image displays blue and yellow fluorescence, along with an elongated crystal. Image by Paul Johnson.
While the specific structure of the 480 nm optical defect is not yet understood, it is known to be associated with yellow fluorescence (Y. Luo and C.M. Breeding, “Fluorescence produced by optical defects in diamond: Measurement, characterization, and challenges,” Summer 2013 G&G, pp. 82–97). The defect is also sometimes attributed to substitutional oxygen in type I diamonds. From our data and test results showing no evidence of laboratory-produced alteration, we can conclude that this stone is a natural and very rare example of a cape diamond mixed with a 480 nm band causing the orange component. @chapter:11