Title: Corundum Inclusions in Gem Diamond Abstract: Figure 1. Left: Face-up image of the 0.13 ct round brilliant diamond. Photo by Mitchell Lyn. Right: Photomicrograph of the largest corundum inclusion exhibiting a slight pinkish color when viewed through a microscope with a diffuser plate. The triple image of the inclusion is due to the diamond’s faceting. Photomicrograph by Garrett McElhenny; field of view 1.76 mm.
Inclusions can tell us a great deal about a diamond’s formation history. Inclusions such as olivine, garnet, and chromite are more common, while others such as kyanite, zircon, and corundum (Al2O3) can be quite rare. Regardless of their rarity, diamond inclusions are often quite fascinating as they trap a small bit of the deep earth that cannot otherwise be sampled.
To our knowledge, the only previously recorded occurrence of chromium-bearing corundum (i.e., ruby or pink sapphire) as an inclusion in a gem diamond was nearly 40 years ago (H.O.A. Meyer and E. Gübelin, “Ruby in diamond,” Fall 1981 G&G, pp. 153–156). In that study, the 0.06 ct round brilliant diamond contained a surface-reaching ruby crystal. The exposed inclusion was analyzed using single-crystal X-ray diffraction, and chemical analysis was conducted using a reference ruby to calculate oxide percentages. At least two occurrences of blue corundum (i.e., sapphire) have also been reported (Summer 2006 Lab Notes, pp. 165–166; M.T. Hutchison et al., “Corundum inclusions in diamonds—discriminatory criteria and a corundum compositional dataset,” Lithos, Vol. 77, No. 1-4, 2004, pp. 273–286).

Here we report the second identification of chromium-rich corundum in a natural gem diamond. This diamond was discovered by Michael Turner at Stuller during routine screening for undisclosed laboratory-grown diamonds. Mr. Turner determined that it was type IIa using FTIR spectroscopy and then noted a peculiar chromium doublet emission in PL. The diamond was sent to the Carlsbad laboratory for further testing. Upon examination, the 0.13 ct round brilliant (figure 1, left) contained at least five internal inclusions that were positively identified as chromium-rich corundum (ruby or pink sapphire). The largest inclusion (figure 1, right) measured 0.18 mm long; the additional inclusions were 0.07 mm or smaller.
When viewed through the microscope with a diffuser plate, the largest of the inclusions displayed a very light pinkish color, while the rest exhibited no visible coloration. A DXR2xi Raman imaging microscope was used to create a map of the individual inclusions. These maps, consisting of thousands of individual Raman spectra, were analyzed and compared to Raman spectra from known corundum samples to determine that at least five of the inclusions in the diamond were in fact corundum (figure 2). A chromium doublet centered around 1369 and 1399 cm–1 (~693 and 694 nm) was also detected in the Raman spectra, further confirming that the corundum contained significant chromium. Also observed in the inclusions were additional luminescence peaks that are not typical of diamond (figure 3). In particular, a 704 nm peak was localized around the corundum inclusions.

Figure 2. Raman spectra identifying the corundum inclusions. The red trace shows the figure 1 (right) inclusion, while the blue trace is a known corundum reference. Spectra vertically offset for clarity.

Figure 3. Left: Photoluminescence spectrum showing the detection of chromium with 532 nm laser excitation. Top right: Photo of the table with the corundum inclusions circled in red. Photo by Mitchell Lyn. Bottom right: False-color PL map generated by the Raman imaging microscope collected from the table in the same orientation showing the 693–694 nm chromium peaks and peak intensities.
After identifying the inclusions, we tested their reaction to UV light. Under illumination from a long-wave ultraviolet light source (365 nm), the largest one displayed a beautiful deep red color (figure 4). Ruby and pink sapphire typically exhibit a weak to strong red color when exposed to long- and short-wave UV due to fluorescence from abundant chromium impurities; the same was observed for some of the corundum inclusions within this diamond. Other corundum inclusions were either too weak to photograph or did not display any visible reaction to UV light.
Previous research by G.R. Watt et al. (“A high-chromium corundum (ruby) inclusion in diamond from the São Luiz alluvial mine, Brazil,” Mineralogical Magazine, Vol. 58, No. 392, 1994, pp. 490–493) and Hutchison et al. (2004) found that inclusions of corundum (colorless, ruby, and sapphire) in their non-gem type II diamonds contained large amounts of chromium and nickel. Both studies declared the diamonds to be sublithospheric in origin with an eclogitic paragenesis due to the association of the corundum inclusions with other deep-mantle inclusions. We did not perform chemical analysis on the inclusions described here because they were entirely encased within the diamond. While we cannot determine the depth of formation for this diamond, it can be reasonably inferred, based on previous studies, to have a sublithospheric origin and eclogitic paragenesis, as Al2O3 is rare in peridotitic mantle. Opportunities to examine diamonds containing rare inclusions provide an intriguing glimpse into the deep earth.

Figure 4. The largest of the corundum inclusions shown with ordinary fiber-optic lighting (left) and long-wave UV illumination (right). The right image displays the corundum’s deep red fluorescence color. Photomicrographs by Garrett McElhenny; field of view 2.34 mm.
It is with great sadness that we note the passing of Michael Turner. Michael was a well-respected contributor to GIA, and he will be dearly missed. Source: GIA @topic:1


Title: Colored Gems, Chinese Jewelry Designers, and Colored Diamond Spectra Abstract: Welcome to the first Gems & Gemology of 2015!

Spring is always an especially busy time, because our first issue comes hard on the heels of the annual Tucson gem shows. This event always provides an illuminating window into the world of colored gem supply and demand. Indeed, articles in this G&G provide a flavor of that worldview, featuring Vietnamese blue spinel, Moroccan amethyst, ruby from Mozambique, and a survey of contemporary Chinese jewelry designs featuring a wealth of colored gemstones.

Our lead article, by French researcher Boris Chauviré and his coauthors, offers geological context and a gemological characterization of the vivid blue spinel from Luc Yen, northern Vietnam, which owes its remarkable color to traces of cobalt.

Next, GIA’s Andrew Lucas and Merilee Chapin partner with Chinese coauthors Moqing Lin and Xiaodan Jia to survey the tremendous progress this country’s jewelry designers have made in the last decade. Informed by their civilization’s rich cultural roots and driven by the power of a rapidly growing domestic consumer market, the artistic prowess of Chinese designers is increasingly evident on the global stage.

Our third article, by a joint Moroccan-Italian team headed by lead author Fabrizio Troilo, provides an introduction to amethysts from Boudi, Morocco. Their study outlines the geology, mining, and the internal and external features of this attractive material.

Our fourth paper, by GIA’s Dr. Jim Shigley and Dr. Mike Breeding, bucks this issue’s colored-gem trend. Their article provides a review of colored diamond spectra, including a foldout chart, which we trust many practicing gemologists will find illuminating.

In addition, we’re delighted to present G&G’s third field report. GIA authors Merilee Chapin, Vincent Pardieu, and Andrew Lucas report on the geology and mining practices at Mozambique’s Montepuez ruby deposit, currently the world’s most important commercial source of ruby.

After these five feature articles, you’ll find our regular Lab Notes and Gem News sections. This issue contains in-depth coverage of the February 2015 Tucson Gem and Mineral shows, along with reports on the recent Gemstone Industry & Laboratory Conference (GILC) and the GIA-sponsored International Diamond School for natural diamond researchers held late January in Brixen, Italy.

We’re also delighted to present the results of the 2014 Dr. Edward J. Gubelin Most Valuable Article Award. Our sincere thanks to everyone who participated—we had an excellent response this year. Please see the results on page 31. Also, please don’t forget to take the G&G Challenge, our annual multiple-choice quiz!

Finally, as many longtime contributors know, Stuart Overlin has been the editorial backbone of our journal for a number of years. I’m very pleased to announce Stuart’s promotion to G&G’s managing editor. I’d also like to thank former managing editor Justin Hunter for his contribution. Justin is moving to an important new role at GIA.

We hope you enjoy this edition! Source: GIA @topic:1


Title: The ABCs of Pearls Reveal Fascinating Aspects of Gems from the Deep Abstract: Nicholas Sturman, senior manager of identification at GIA in Thailand, spoke on pearls at GIA’s 114th Gemstone Gathering in Bangkok. Photo by Lhapsin Nillapat/GIA

Pearls are unique among gemstones because they are created by living organisms and need minor additional processing before they are placed in jewelry. There are many little known and fascinating facts about pearls that are sure to pique your curiosity about them.
Nicholas Sturman, senior manager of identification at GIA in Thailand, gave a presentation on pearls to students and members of the jewelry trade in Bangkok on Dec. 19 at GIA’s quarterly GIA Gemstone Gathering. The talk, “The A-Z of Pearls,” covered at least one pearl-related subject for each letter of the alphabet.
He began with abalone for “A” for example, while “fluorescence” and “pigment,” represented the letters “F” and “P,” respectively. His goal was to encourage attendees to think more deeply about pearls.
This appeared to work with some of the guests, since comments like “I didn’t know there was so much variety in mollusks and pearls” and “I think I need to check out what GIA offers in the way of pearl courses” were overheard during the post-talk hands-on showing of various mollusks and pearl samples that were brought along to further educate the attendees.

Sturman and some of his team (back right) look at and discuss pearl and mollusk samples with some of the attendees. Photo by Lhapsin Nillapat/GIA
“It is always rewarding to see participants benefit in even the slightest way from such events,” Sturman said. “Hopefully the experience will lead them onto further research into some of the subjects covered and open their eyes to the fascinating world of pearls.”
GIA offers a pearl course where these details and many others may be learned. The course is ideal for anyone who wants to study more about this branch of gemology or wants to go deeper into the subject so that they can better serve their pearl buying clients. Source: GIA @topic:5


Title: Rare Stones In Demand Abstract: Brightly colored sphalerite is one of the most popular “unusual” gems sold by Coast-to-Coast. Photo by Duncan Pay/GIA; courtesy of Coast-to-Coast Rare Stones International.

For Brad Wilson and John Bradshaw (Coast-to-Coast Rare Stones International, Kingston, Ontario), their inventory of corundum and other familiar gemstones never makes the trip to Tucson. Instead, their showcases are filled with rarities such as afghanite, bastnaesite, beryllonite, clinohumite, celestite, hambergite, magnesite, montebrasite, pargasite, sphalerite, violane, and zincite. These stones often are soft and near-colorless and have cleavage, making them less desirable for jewelry. But for a collector or a designer looking for the unusual who understands how to work with such challenging stones in jewelry, Coast-to-Coast at GJX is a worthwhile destination.

	Coast-to-Coast Rare Stones International

In his interview, Coast-to-Coast’s Brad Wilson explains that rare gems have a place in jewelry, too. Innovative designers seek out rare materials such as sphalerite, sphene, apatite, and even afghanite for clients who appreciate the unusual.
Some of the lesser-known stones available at Coast-to-Coast included datolite, cobaltocalcite, faceted aragonite, and tenebrescent scapolite. Fluorescent opal was a noteworthy new find. Under ordinary interior lighting, this opal is near colorless to very pale yellow. It can fluoresce bright green in response to the small UV component in ordinary daylight. Placed under an ultraviolet light or 405 nm laser, the fluorescent effect is spectacular.

With unfamiliar collectors’ stones, colorful varieties usually sell best. Wilson’s more popular items for this show included sphene, sphalerite, and apatite. He told us that other stones rise and fall in popularity. One example is tugtupite, a rosy-pink mineral, usually found in aggregate form, that exhibits both interesting fluorescence and tenebrescence. It sold out on the first day in previous shows, according to Wilson, but in 2015 only a few had sold by the third day. Source: GIA @topic:1


Title: Turquoise United Conference 2023 Abstract: Figure 1. From left: Jacob Lowry, Sean Hyrons, Matthew Wernz, and Kenneth Van Wey engage in a panel discussion titled “Laws: Liabilities and Protections.” Photo courtesy of the Turquoise Museum.
The second annual Turquoise United conference was held August 10–12, 2023, at the Albuquerque Convention Center in New Mexico. The vision of the conference is to bring together members of the turquoise industry at a single event for discussion and reunion. With this goal in mind, the conference caters to every aspect of the turquoise industry, attracting miners, lapidaries, collectors, dealers, artists, treatment experts, and researchers. A year ago, GIA representatives attended the inaugural Turquoise United conference (Fall 2022 GNI, pp. 390–394).
This year, there were additional symposium sessions across a range of topics and new competitions for registered conference participants. The first session was hosted by Turquoise Museum executive director Jacob Lowry, with a panel consisting of Kenneth Van Wey (Indian Arts and Crafts Board), Matthew Wernz (Federal Trade Commission), and Sean Hyrons (U.S. Fish and Wildlife Service). The panel discussed the laws surrounding the sale and purchase of turquoise jewelry and gave examples of situations in which their respective agencies may become involved (figure 1). The panelists offered advice to consumers purchasing turquoise jewelry, noting the importance of a written receipt stating the authenticity and nature of the product in as much detail as possible.
The turquoise grading system proposed by Joe Dan Lowry at last year’s conference has been put into practice. Attendees could attempt to grade sample stones or stones of their own using the system based on turquoise master stone sets and grades of color, matrix, and “zat” (boldness and dynamism). Application of the grading system requires detailed knowledge of certain turquoise features present at different mines. For example, author AG did not recognize “waterweb” matrix as being a valuable pattern, and therefore gave a lower matrix score on a stone with a high value. The grading system continues to be developed with feedback from the conference, with a goal of publicly accepted use by 2027.
The conference also offered courses for attendees. A “Turquoise Basics” course taught by Jacob Lowry described the types of turquoise and turquoise imitations in the market to better inform new buyers of the stone. Joe Dan Lowry taught a class called “Collecting 101,” offering guidance to consumers beginning their own turquoise collection. A follow-up course, “Collecting 102,” is planned for Turquoise United 2024.

Figure 2. Mark Baca (American Turquoise Online) holds his winning piece (right) and trophy for Best in Show. Photo courtesy of the Turquoise Museum.
Some attendees were rewarded for their impressive specimens and extensive turquoise knowledge. A highest-grade turquoise stone contest received numerous entries from multiple mines, ranging from natural cabochons with striking color and matrix to hefty rough turquoise nuggets. Best in Show winner Mark Baca (American Turquoise Online) received a monetary prize and trophy (figure 2). An identification contest over both days of the conference allowed attendees to test their skills at identifying the nature and mine origin of turquoise specimens. Michael Turano (Michael Turano Lapidary) won the contest, with Dye Masaki (Native Spirit) placing second, and Ty Gibson (Gibson Lapidary, LLC) in third.
Author AG presented his research on the Mona Lisa mine, located in western Arkansas, in a session on August 11. He provided details about the history, geology, mineralogy, and current mining operations at the site. Discussion about the methods used and Mona Lisa turquoise’s potential place in the market followed the presentation. Material from the mine was also on display at the Turquoise Museum, where the day ended with the Collectors’ Circle Gala.
The following morning, author AP presented GIA’s methods for identifying turquoise in the gemological laboratory. Attendees expressed their interest in learning more about these techniques and shared their views on terminology in the turquoise industry.
Next, Joe Dan Lowry presented a session on the challenges of fingerprinting turquoise mine sources, especially in archaeological contexts. The heterogeneity of turquoise, the multitude of sources, and the stone’s formation in near-surface, sedimentary environments create unique challenges when trying to determine a stone’s mine origin.

Figure 3. Left: A conference participant examines turquoise cabochons. Right: Iranian turquoise cabochon with a brown “spiderweb” matrix pattern. Photos by Aaron Palke.
Throughout the conference, a gem show focused solely on turquoise was open to the public. Roughly a dozen dealers participated, offering a wide variety of turquoise material (figure 3), including high-end jewelry pieces, natural rough material, untreated cabochons, stabilized cabochons, and beadwork. Many American turquoise localities were represented, while turquoise from Iran, China, Egypt, and Mexico was also available. A silent auction allowed conference attendees to bid on natural turquoise and turquoise jewelry pieces donated by the event sponsors.
The conference concluded with a banquet honoring the first inductees into the Turquoise Hall of Fame: Joseph Pogue, Leonard Hardy, Robert Zachary, Philip Chambless, and James Elquist. These honorees were nominated for their impact on the turquoise industry. The event sponsors reiterated their desire to grow Turquoise United, with confirmation that the annual event will be hosted in Albuquerque in 2024. Source: GIA @topic:7


Title: Turquoise Planet Earth Abstract: An 84.90 ct sphere of Armenian turquoise measuring 23.70 × 23.88 × 23.91 mm displays a striking resemblance to planet Earth. Left: Diffuse fiber-optic lighting allows the face of the stone to be seen in full. Right: Pinpoint fiber-optic lighting creates an appearance of day and night cast onto Earth. Gifted to GIA’s colored stone reference collection by Gemfab CJSC. Photos by Britni LeCroy.
Armenia is not a widely known source of turquoise, but a recent donation to GIA’s colored stone reference collection proved that the country can produce high-quality, aesthetically pleasing stones. One of them, cleverly cut into an 84.90 ct sphere measuring 23.70 × 23.88 × 23.91 mm, bore an astonishing resemblance to planet Earth (see above). The natural brown matrix material mimicked the continents, while the greenish blue turquoise represented the oceans. Infrared spectroscopy showed that, like most gem turquoise, the specimen had been polymer impregnated, a treatment that makes the stone more durable. Additionally, no dye was detected. To accentuate its likeness to our planet, the sphere was photographed against “Musou Black,” marketed as the world’s blackest fabric and advertised to absorb 99.905% of all light. Precise placements of pinpoint lighting created various appearances of a sunlit Earth suspended in space. Source: GIA @topic:2


Title: Unusual Colored Stones Abstract: These rare gemstones were recently examined at GIA’s Carlsbad laboratory. From left to right: a 0.87 ct green adamite, a 0.73 ct brown bahianite, a 42.08 ct light brownish yellow cerussite, a 0.33 ct purple chambersite, a 2.45 ct orange olmiite, and a 1.30 ct color-change remondite. Photo by C.D. Mengason.

	Recently, a parcel of approximately 40 rare gemstones was submitted to GIA’s Carlsbad laboratory for identification. Six of these stones represented gem types that had never been examined at this location. They were identified using standard gemological testing, Raman spectroscopy, and energy-dispersive X-ray fluorescence (EDXRF).

	A 0.87 ct translucent green hexagonal step cut was identified as adamite, Zn2(AsO4)(OH). It had a specific gravity (SG) of 4.40 and a refractive index (RI) of 1.721–1.750. The stone fluoresced weak green under long-wave UV light but was inert to short-wave UV, which is atypical of adamite. Clouds and fractures were observed with 30× magnification.

	A translucent brown trapezoidal step cut with an SG of 5.18 proved to be bahianite, Al5SbO14(OH)2, which is especially rare as a facet-grade gemstone. The 0.73 ct bahianite had a refractive index over the limit (OTL) of the RI liquid. It was inert under long-wave UV light but displayed very weak blue under short-wave UV light. Large fractures, along with numerous whitish fibrous, radial, and granular inclusions and some surface-breaking opaque metallic inclusions, were visible using 30× magnification. It also displayed vitreous to subadamantine luster.

	A 42.08 ct transparent light brownish yellow octagonal mixed-cut specimen with an SG of 6.54 displayed an OTL refractive index and a biaxial optic figure, indicating its doubly refractive nature. It was inert to long-wave UV light but fluoresced very weak yellow under short-wave UV light. Magnification revealed strong doubling, strong fire, and numerous growth tubes and needles. Its heft was high due to its lead content. These properties, along with advanced testing, led to its identification as cerussite, PbCO3. Although cerussite is a common weathering product of lead ore minerals, its softness, brittleness, and heat sensitivity make it a very rare faceted gem, particularly in this large size.

	Another stone from the collection, a 0.33 ct transparent to semitransparent purple triangle step cut with an SG of 3.49 and an RI of 1.728–1.734, was determined to be chambersite, Mn3B7O13Cl. The gem was inert to both long- and short-wave UV light and showed numerous clouds with 30× magnification. Chambersite is an extremely rare mineral, found as deep as 70 feet in salt brines (J.E. Arem, “Chambersite,” The Color Encyclopedia of Gemstones, 1987, 2nd ed., p. 65). Because it is so small and dark, this material is almost never faceted.

	A 2.45 ct semitransparent orange cushion modified brilliant was identified as olmiite, CaMn[SiO3(OH)](OH), which was first discovered in 2006 in South Africa (http://www.mindat.org/min-30762.html). Its SG was 2.95. The stone was doubly refractive, displayed an RI of 1.648–1.671, and fluoresced very weak orangy red under both long- and short-wave UV light. Magnification revealed wavy graining, fibrous dislocations and inclusions, and a slightly oxidized stone surface. Most olmiite crystals are not suitable for faceting.

	The final stone of the six, a transparent pear-shaped modified brilliant that changed from greenish yellow under fluorescent light to yellowish orange under incandescent light, was identified as color-change remondite, Na3(Ce,La,Ca,Na,Sr)3(CO3)5. The 1.30 ct stone had an SG of 3.40 and showed an RI of 1.628–1.631, yielding a birefringence of only 0.003. It was inert to both long- and short-wave UV light. Handheld prism spectroscopy revealed a strong rare earth element spectrum. Large growth tubes, scattered particles, and etch channels were observed with 30× magnification. The stone’s rounded facet junctions indicated a low hardness. Remondite was previously reported as a color-change burbankite-related mineral from Quebec (Winter 1992 GNI, pp. 270–271).

	Such a suite of gemstones, prized among avid gem collectors, is not often submitted to the laboratory. Without the help of advanced analytical equipment such as Raman spectroscopy and EDXRF to complement standard gemological testing, it would be challenging to conclude the identity of these rare gemstones. Source: GIA @topic:2


Title: Inaugural Turquoise United Conference Abstract: Figure 1. Left: The entrance to the Turquoise Museum. Photo by Jacob Lowry/Turquoise Museum. Right: A corner in the origin display room shows rough and polished samples from Tyrone and Cerrillos, two well-known deposits in New Mexico. Photo by Tao Hsu.
The first-ever Turquoise United conference was held August 11–13, 2022, in Albuquerque, New Mexico. This multifaceted event was organized and hosted by Joe Dan Lowry and his son Jacob, part of a fifth-generation family in the turquoise industry. All activities took place in the Turquoise Museum (www.turquoisemuseum.com), owned and operated by the family and the Albuquerque Convention Center (figure 1).

Figure 2. Russell Twiford III holds a massive resin imitation of turquoise he created, which is now displayed at the Turquoise Museum. Photo by Aaron Palke.
Turquoise has been treasured and used by many different cultures for thousands of years. As an aggregate gemstone, it also poses a challenge for traders. Possibly more so than for any other gemstone, the buying, selling, and owning of a turquoise piece can be an intensely personalized experience. A combination of factors including color, matrix pattern, specific mine origin, and the presence or absence of treatment come into play, making each piece unique. Turquoise United provides a platform for everyone involved in the trade to gather as a community and discuss important topics. About 100 delegates from different countries attended the inaugural event, including miners, cutters, treatment experts, dealers, television shopping network suppliers, collectors, jewelry designers, enthusiasts, consumers, appraisers, and scientists. GIA sent research and education representatives to connect with the turquoise community and learn from the experts. We had the opportunity to interview over 10 industry experts, including members of the domestic and international trade, miners, and artisans involved in turquoise treatment and the manufacture of imitation turquoise (figure 2). The content gathered will be highlighted in future GIA educational programs.

Figure 3. Left: Attendees enjoy a conversation about Southwestern-style jewelry design and manufacture outside the Turquoise Museum. Right: Joe Dan Lowry and son Jacob were the auctioneers at the kickoff gala. Photos by Tao Hsu.

Figure 4. A 9.32 ct backed turquoise from Yungaisi, China, purchased during the auction at the Turquoise United conference. Photo by Aaron Palke.
A wide variety of activities made this educational conference enjoyable. An evening gala and auction kicked off the event (figure 3). Auction items included finished turquoise pieces, specimen and finished stone sets, and a bracelet featuring more than 200 inlay pieces designed and donated by GL Miller (Studio GL, Albuquerque). All other items were provided by the museum, and the proceeds will be allocated for future Turquoise United events. Delegates had the opportunity to view representative items from domestic and international sources such as Yungaisi, China (figure 4). All items were auctioned by the end of the gala. Each attendee received a gift bag containing a piece of turquoise, including some nice cabochons.

Figure 5. Turquoise enthusiasts and consumers brought their jewelry pieces to the identification panel experts, who shared their opinions on the pieces and answered questions from the audience. Photo by Tao Hsu.
During the day sessions, experts including Joe Dan Lowry, GL Miller, and author AP hosted identification panels at the Turquoise Museum (figure 5). Panelists evaluated the identity and origin of various turquoise jewelry pieces submitted by participants. The panel attracted consumers and enthusiasts who shared the stories behind their treasures. In the turquoise collector community, mine origin is an extremely important aspect. Turquoise enthusiasts often spend a lifetime putting together a collection of quality pieces from the most important turquoise mines, especially from the American Southwest. Lowry and Miller impressed the audience with their knowledge of historic turquoise mine characteristics, and engaged in much discussion about the complexity involved in conclusive identification and origin determination.
Two evening discussion panels took place in the Albuquerque Convention Center, with one focused on the vision and educational function of Turquoise United and the other on turquoise grading. The authors participated in both panels along with delegates from all aspects of the industry. Author TH noted the current lack of turquoise-related educational programs and the potential industry benefit of reaching a broader audience not limited just to turquoise traders.

Figure 6. Top: Joe Dan Lowry proposes a turquoise grading system alongside a panel of experts. Photo by Tao Hsu. Bottom: A look at the color scale and master stones for blue turquoise included in Lowry’s grading system. Photo by Joe Dan Lowry.
The second panel centered on Joe Dan Lowry’s proposal for a turquoise grading system that could be applied inside and outside of the turquoise community (figure 6). Lowry’s grading system is based on an unsurpassed collection of turquoise master stones of various qualities from global sources accumulated by the Lowrys over five generations. In the proposed grading system, origin is considered separately from other quality factors. A scoring system is based on a scale of 0 to 100, with the most important factor being color (70% of the final score) and additional consideration given to the aesthetics of the matrix (20%) as well as “zat” (10%), a combined description of the dynamic and boldness of both the color and the matrix patterns. Different levels of “zat” can be described as dynamic and bold in contrast to dull, flat, or uninteresting. After the quality evaluation and considering the importance of origin in many cases, the result would be combined with the condition of the piece (treated or untreated), cut, weight, and backing to give the buyer a complete picture of the stone. The panelists had a lengthy discussion on the applicability of the grading system, and author AP shared his views on consistency and potential market impact with the attendees.

Figure 7. Left: A turquoise show attendee checks out polished pieces from multiple southwestern U.S. deposits. Photo by Tao Hsu. Right: An assortment of high-quality natural Persian turquoise cabochons; the one being held weighs about 19 ct. Photo by Aaron Palke.
In addition to the educational activities, a small-scale turquoise show took place in the courtyard of the museum. A dozen dealers participated, displaying rough and finished turquoise to attendees (figure 7). To keep the event focused, dealers could only sell turquoise stones and not finished jewelry. Turquoise from the southwestern United States, Mexico, China, and Iran were all featured at the show.

Figure 8. The historic Tiffany mine in the Cerrillos mining district. This pit was mined many hundreds of years ago by Native Americans before contact with European cultures. Photos by Aaron Palke.
Surrounded by historic turquoise mines (figure 8) and Native American communities that have contributed enormously to the popularity of turquoise in the United States through their iconic turquoise jewelry designs, Albuquerque was the perfect setting for the conference. The annual Santa Fe Indian Market (SFIM), held every August, is also in close proximity. This year marks the hundredth anniversary of this famous event celebrating Native American arts and fashion, which features turquoise and turquoise jewelry. While the second Turquoise United conference is set for Albuquerque, the Lowrys are already planning future events and considering other important turquoise centers to host the conference as well. Source: GIA @topic:7


Title: Turquoise from Western Arkansas Abstract: Figure 1. Recent production from a reactivated turquoise deposit in Polk County, Arkansas. The beads shown here measure up to 25 mm in diameter, while the largest cab weighs 30 ct. Photo by Robert Weldon/GIA.

At their AGTA booth, Avant Mining (Jessieville, Arkansas) displayed an unexpected material: turquoise from Polk County, Arkansas. According to owner James Zigras, this is the only gem-quality turquoise deposit in the U.S. located outside the Southwest. Calibrated goods and specimens ranging from blue-green to greenish blue were on view (figure 1). Also at the booth was a 245 lb. boulder unearthed in 1982 and polished in 2018 by Michael Beck (Copper Canyon Lapidary & Jewelry, Sedona, Arizona). The boulder, shown in figure 2, is the largest known American turquoise nugget.

Figure 2. This 245 lb. boulder of turquoise, removed from the Polk County deposit in 1982, is the largest known American turquoise nugget. Photo by Robert Weldon/GIA.
The source was first mined from 1978 to 1986 under a previous owner, but the material was likely sold as Southwestern turquoise. During these years, there was too much competition in the market for stabilized turquoise, and activity eventually ceased. In 2017, Zigras bought the previous owner’s estate, which included two tons of turquoise rough, and restaked a claim on the original mining site. He expected the source to yield planerite and was surprised to find that the material was close to ideal for the turquoise end member of the planerite-turquoise solid solution series. In January 2018, a test trench was worked for seven days. In that time, the deposit produced approximately 1,000 lbs. of turquoise and an old mine shaft was uncovered. Veins are located about 10 feet below the surface (see video below). Quartz crystals and wavellite are also found in the deposit.

Turquoise VeinsThe veins of turquoise are close to the surface of the Arkansas deposit, as seen in this short video.
Zigras indicated that the turquoise is impregnated but not dyed. Independent testing at GIA confirmed impregnation; no evidence of dye was detected on the samples. Zigras plans to submit the material for Zachery treatment, a process designed to improve the polish and color of turquoise. It will be interesting to see this source’s output in the coming years. Source: GIA @topic:1


Title: Oiled Tanzanite Abstract: This large 115 ct tanzanite was found to contain oil (left). After removal of the oil (center and right), highly reflective fissures became obvious. This clearly demonstrates how oiling a gem can have a radical impact on its appearance. Photos by Chanon Yimkeativong.

Over the past five years, gemologists at Bangkok’s Lotus Gemology have seen increasing numbers of what we might call “non-traditionally” oiled gems. This is particularly true of, but not limited to, Burmese gems such as ruby, sapphire, and spinel. But it is important to note that any gem with surface-reaching fissures can be oiled, often with dramatic improvements in apparent clarity. Cuprian and rubellite tourmalines are also frequently enhanced in this way.
Recently we received a faceted tanzanite weighing more than 100 carats for testing. As is our practice for non-emeralds exhibiting fissure-filling clarity enhancement, we photograph the gem and then allow the client to resubmit the stone after filler removal. The figure above clearly shows the dramatic effect that fissure filling with oil/resin can have on gems such as tanzanite, even where the refractive index of the filler does not closely match that of the gem. Source: GIA @topic:3


Title: Tanzanite History and Lore Abstract: This 122.70-carat tanzanite is in the collection of the Smithsonian National Museum of Natural History. - Chip Clark, courtesy Smithsonian Institution

Tanzanite is relatively new to the colored stone galaxy. As the most common story of the tanzanite mining boom goes, in 1967 a Masai tribesman stumbled upon a cluster of highly transparent, intense violet-to-blue crystals weathering out of the earth in Merelani, an area of northern Tanzania. He alerted a local fortune hunter named Manuel d'Souza, who quickly registered four mining claims.

D’Souza hoped that he’d been shown a new sapphire deposit. Instead, the deposit contained one of the newest of the world’s gems.

Although it’s a newcomer to the gemstone industry, tanzanite has quickly become one of the most popular colored gemstones. - Courtesy Richard Krementz Gemstones
Within a short time, 90 more claims appeared in the same 20-square-mile area. No one was quite sure what the beautiful crystals were, but everyone wanted to lay claim to the profits they were certain to produce. The new gem would eventually be known as tanzanite, and it would, at times, rival the Big 3 in popularity.

Tiffany & Company recognized its potential as an international seller and made a deal to become its main distributor. Tiffany named the gem after the country it came from, and promoted it with a big publicity campaign in 1968. Almost overnight, tanzanite was popular with leading jewelry designers and other gem professionals, as well as with customers who had an eye for beautiful and unusual gems.

The instant popularity of this transparent blue-to-violet gem was tied to its vivid color, high clarity, and potential for large cut stones. Source: GIA @topic:1


Title: Turquoise History and Lore Abstract: This 15th-16th century icon of Mexican (Aztec) art, was probably worn on the chest on ceremonial occasions. ©The Trustees of the British Museum

                      Turquoise is one of the world’s most ancient gems. Archaeological excavations revealed that the rulers of ancient Egypt adorned themselves with turquoise jewelry, and Chinese artisans were carving it more than 3,000 years ago. Turquoise is the national gem of Tibet, and has long been considered a stone that guarantees health, good fortune, and protection from evil.

The gem’s name comes from the French expression pierre tourques, or “Turkish stone.” The name, which originated in the thirteenth century, reflects the fact that the material probably first arrived in Europe from Turkish sources.

Turquoise was a ceremonial gem and a medium of exchange for Native American tribes in the southwestern US. They also used it in their jewelry and amulets. The Apaches believed that turquoise attached to a bow or firearm increased a hunter’s or warrior’s accuracy.

	A turquoise and silver buckle and trim give a Southwestern flair to this leather belt.
Turquoise is plentiful and available in a wide range of sizes. It’s used for beads, cabochons, carvings, and inlays. Although well known to consumers, its popularity in the mainstream jewelry industry comes and goes. The biggest and most permanent market is in the American Southwest. It’s also popular elsewhere, among customers who are captivated by that region’s mystery and romance, as well as by the blue of its skies.

	Turquoise combines with sapphire, carved emeralds, rubies, and diamonds in this charming “Bird of Paradise.” This 18-karat gold clip brooch was made in the mid-1940s. - © GIA & Tino Hammid, courtesy private collector
In the United States, turquoise is one of the birthstones for December. (Zircon is the other option for that month).

	This Hungarian cuff bracelet combines enameling with lovely turquoise cabochons. - Courtesy Ginger Moro Source: GIA @topic:1


Title: Tanzanite Quality Factors Abstract: Tanzanite is one of the most popular colored gemstones in the world.- Courtesy Tanzanite Foundation ™

Tanzanite is a versatile gemstone that comes in a variety of sizes and cutting styles. Although it was only discovered in the late 1960s, it has quickly established itself as one of the premier gemstones in the world.

Color
Tanzanite is a pleochroic gem, which means it can show different colors when viewed in different crystal directions. This makes cutting a crucial element in determining the color the consumer sees when the stone is cut and set in jewelry.

Tanzanite’s color can be a very bright, intense blue.
In exceptional tanzanites, the color is an intense violetish blue with red flashes of pleochroic color coming from within the stone. Due to the gem’s strong pleochroism, fashioned examples typically show a mix of both blue and violet colors in a wide range of tones. As with most colored gemstones, paler colors are more available and affordable than saturated ones.

In this crystal direction, this tanzanite's violet-to-purple pleochroic color is evident. - Jeff Scovil
Untreated, tanzanite is typically brownish. Most blue tanzanites for sale today owe their color to heat treatment, which is what reveals the gem’s attractive pleochroic blues and violets. The blue crystals originally discovered by Masai tribesmen were an exception because they’d probably been exposed to a natural heat source within the earth at some point.

As trade professionals assume the majority of the tanzanite on the market has been heated in some way, there’s little effect on pricing. In many cases, it’s challenging for gemological laboratories to determine whether a tanzanite has been heated.

Clarity
Much of the tanzanite sold for jewelry has inclusions that can be seen only under magnification, so any eye-visible inclusions cause a drop in value.  Also, any inclusions that might pose durability problems, such as fractures, lower tanzanite value greatly.

Most tanzanites cut as faceted gemstones for use in jewelry contain no inclusions that are visible to the eye. - Courtesy Tanzanite Foundation ™

Rarely, tanzanite can contain inclusions that cause a cat’s-eye effect.
Cut
Cutting plays an important role in tanzanite’s color display. Because of its pleochroism—the ability to show different colors when viewed in different crystal directions—cutting direction determines the gem’s overall face-up color.

This award-winning jewelry piece features two triangular tanzanites set back to back. The stones were cut with the proper orientation and proportions to allow maximum enjoyment of their deep violet blue color. - Courtesy Tanzanite Foundation ™
Cutters consider financial realities when they decide how to cut tanzanite. As with other gems, weight lost is profit lost. Cutting a tanzanite to emphasize the violet-to-purple color usually wastes less rough than cutting it to get a violetish blue color. That's part of the reason face-up violet-purple tanzanites are more plentiful than specimens with a stronger blue color component.

Tanzanite is sometimes cut in designer fantasy styles. - Courtesy Mark Schneider
But this decision must be balanced against the higher per-carat price that the finer violetish blue color might bring. The cutter essentially makes a choice between a smaller top-color gem and a larger violet-purple one.

Carat Weight
Tanzanite is available in a wide variety of sizes, shapes, and faceting designs. The finest and deepest colors are usually seen in sizes over 5 carats. Smaller stones are often less intense in color.

Tanzanite can be found in large sizes for jewelry use. This is a square-cut 37.07-carat stone - Courtesy Robert Kane, Fine Gems International

This suite of tanzanite jewelry has a total weight of 500 carats. - Courtesy Intercolor Source: GIA @topic:1


Title: Turquoise Quality Factors Abstract: The green turquoise cabochon, from an American mine, might become part of a designer’s unique jewelry piece. The even blue color of the cabochon on the right would be called “Persian blue” in the trade. Photo: Robert Weldon/GIA, Dr. Eduard J. Gübelin collection.

Fine-quality turquoise is sought after around the world by designers of unusual jewelry pieces.

Typically, turquoise is judged on three basic quality factors—color, texture, and the presence or absence of matrix.
Turquoise Color
Blue Turquoise
The most-prized turquoise color is an even, intense, medium blue, sometimes referred to as robin’s egg blue or sky blue in the trade. The traditional source for this color is the Nishapur district of Iran, so you’ll also hear it described as “Persian blue,” whether or not it was actually mined in Iran.

Green Turquoise
Generally speaking, turquoise with a green to greenish blue color is less desirable than turquoise with a pure blue hue, but it depends on personal preference. There are some contemporary designers who actively seek avocado and lime green turquoise.

The turquoise in the brooch and graduated bead strands is from Arizona’s Sleeping Beauty Mine. Its smooth, even color represents the appearance prized by most collectors. - Photo: Valerie Power/GIA. Courtesy: GLEAM
- Courtesy GLEAM
Turquoise Pattern
Turquoise can be semitranslucent to opaque, with a color that usually ranges from light to medium blue or greenish blue. It’s often mottled and sometimes has dark splotches. It might also have veins of matrix running through it (matrix is a remnant of its surrounding rock). The material known as spiderweb turquoise contains fine seams of matrix that form attractive web-like patterns.

These free-form turquoise cabochons show a typical matrix pattern. Photo: GIA
The most valuable turquoise is an even medium blue, with no matrix and the ability to take a good polish.
Turquoise Cut
Turquoise is most often cut as a cabochon. The smoothly rounded dome shape sets off turquoise’s color, texture, and any matrix beautifully. In addition, manufacturers and artisans fashion turquoise into round or oblong beads for strand necklaces, and into small, flat pieces that are popular in jewelry inlays. Some top-color blue turquoise is engraved with Persian or Arabic inscriptions, inlaid with gold. Lower-quality rough material might be tumbled into “nuggets."

This stylish and unusual “Pegged Nugget” bracelet contains about 100 flat turquoise nuggets that are attached with flat silver pegs. -– Photo: Maha Tannous/GIA. Gift of Robert Lee Morris

This intarsia box created by Nicolai Medvedev includes flat pieces of turquoise as part of its inlaid design. -– Photo © GIA & Tino Hammid, gift of Carol and Fred Seeman
Turquoise Carat Weight
Turquoise is weighed in carats, and five carats equal one gram. Turquoise is available in a wide range of sizes. All sizes, even very small stones, are used in Native American jewelry, and large pieces of turquoise rough are popular for carvings. For any size, the quality and evenness of the color is the overriding value factor.

A single large piece of rough can yield severalmuch smaller pieces of fine, evenly colored turquoise. A gem cutter has to work around the host rock to avoid ending up with a much less valuable gem. Photo: GIA, Dr. Eduard J. Gübelin collection. Source: GIA @topic:1


Title: Turquoise Description Abstract: This 18-karat gold collar, designed by Pierre Touraine, is set with a turquoise cabochon of fine texture and color. - Gift of Touraine Family Trust

                      Turquoise is found in only a few places on earth: dry and barren regions where acidic, copper-rich groundwater seeps downward and reacts with minerals that contain phosphorus and aluminum. The result of this sedimentary process is a porous, semitranslucent to opaque compound of hydrated copper and aluminum phosphate.
Turquoise is a prime example of an opaque colored stone that can be marketed both as a gem for jewelry and as an ornamental material.

	The Abdurreza turquoise mine lies in a dry, remote area of Iran.
Turquoise might lack the sparkle and clarity of transparent colored gemstones like ruby, emerald, and sapphire, but its multi-layered history and soul-satisfying color make it a desirable gem. Its color can range from dull greens to grass greens to a bright, medium-toned, sky blue. People value turquoise highly for its combination of ancient heritage and unforgettable color.

The traditional source for the top color, sometimes described as robin’s-egg blue or sky blue, is the Nishapur district of Iran, the country formerly known as Persia. So, quite often, you’ll hear people in the trade call turquoise of this beautiful color “Persian blue,” whether or not it was actually mined in Iran.

Top-quality turquoise has inspired designers to create elegant jewelry. It’s most often cut into cabochons, but it might also be cut into beads or flat pieces for inlays.

Although much turquoise jewelry is sleek and modern, many US consumers are familiar with the traditional jewelry of Native American peoples such as the Pueblo, Hopi, Zuni, and Navajo. People interested in Native American arts and crafts frequently collect this stylized silver jewelry.

	Elaborate silver and turquoise squash blossom necklaces like this are prized by collectors
	of Native American jewelry. - Courtesy Jaime Steelman
Turquoise is relatively soft, so it’s ideal for carving. Artists in Europe, Asia, the Middle East, and the Americas choose turquoise as a medium for carved jewelry and art objects. It’s often fashioned into talismans with Native American significance, such as bird and animal carvings, called fetishes.

	Native American jewelry often features carved turquoise birds and animals, called fetishes.
	- Courtesy Jaime Steelman
Turquoise owes its texture to its structure and composition. It’s an aggregate of microscopic crystals that form a solid mass. If the crystals are packed closely together, the material is less porous, so it has a finer texture. Fine-textured turquoise has an attractive, waxy luster when it’s polished. Turquoise with a less-dense crystal structure has higher porosity and coarser texture, resulting in a dull luster when it’s polished.

	Turquoise is soft enough to be carved. This turquoise from China was crafted into an
	ornate vase. – Courtesy Geological Museum, Beijing, China
Porosity and texture don’t just affect appearance: They also affect durability. Turquoise is fairly soft—it ranks 5 to 6 on the Mohs scale. Turquoise with a coarse texture might have poor toughness, too. Samples with finer texture have fair to good toughness.

	This Van Cleef & Arpels ballerina brooch and matching clip earrings are designed with gold, diamonds, turquoise, and ruby. - © GIA & Tino Hammid, courtesy private collector
In turquoise, low porosity and fine texture are more valuable than high porosity and coarse texture. Coarse, porous stones are usually treated to make them smoother, shinier, and more marketable.

	The smooth, waxy luster of these turquoise earrings results from closely grouped crystals that lessen porosity. - Courtesy GLEAM
Turquoise deposits usually form in iron-rich limonite or sandstone. Limonite creates dark brown markings in turquoise, while sandstone creates tan markings. These markings are remnants of the host rock within the turquoise, and can resemble splotches or veins. They’re called matrix.

	Turquoise is generally embedded in its host rock, like this specimen from Iran.
Manufacturers try to fashion turquoise so that no matrix is visible, but sometimes it’s unavoidable. Small amounts of turquoise might be scattered through the host rock in such a way that the rough material can’t yield any cut specimens large enough to fashion into gems without including some matrix.

	The matrix in spiderweb turquoise is attractively arranged in a network of thin lines.
The presence of matrix can lower the value of turquoise, but that doesn’t mean turquoise with matrix is worthless or unmarketable. Some buyers actually prefer the presence of matrix in fashioned turquoise if its effect is attractive and balanced.

This is especially true if it’s a type of turquoise known in the trade as spiderweb turquoise. It contains matrix in thin, delicate, web-like patterns across the face of the gemstone. The patterns provide a dark contrast to the gem’s bright blue.

In the market for top-quality turquoise, stones with no matrix at all command the highest prices. Gems with attractive spiderweb matrix rank second in value. Source: GIA @topic:1


Title: Tanzanite 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. Source: GIA @topic:7


Title: Tanzanite Description Abstract: Tanzanite can have an intense and deep violetish blue color.

Tanzanite is the violet blue to blue violet variety of the mineral zoisite. It is mined commercially only in one area of the world: the Merelani Hills of Tanzania, which is where it gets its name.

When blue-to-violet crystals were first discovered in Tanzania in the 1960s, no one
was quite sure what the new crystals were. Careful gemological study determined
that they were a transparent variety of zoisite, and the gem came to be known as
tanzanite. - Jeff Scovil, courtesy Marcus Budil Collection
Tanzanite's appearance is influenced greatly by its pleochroism, which is the ability of a gemstone to show different colors when viewed in different crystal directions. Tanzanite's pleochroism was documented in scientific papers not long after its discovery. In 1969, American Mineralogist described the gem's pleochroic colors as `red-violet, deep blue, and yellow green.' Today, most gems are heat treated, which removes or reduces the yellow green or brownish pleochroic color, maximizing the blue and violet.

Top-quality tanzanite can be violetish blue --similar to a fine sapphire color --or a unique, predominately violet hue all its own. Some stones might also appear more purplish depending on how the cutter chooses to orient the fashioned gem. Both the violet and blue pleochroic colors are readily visible in a fashioned stone when it is gently rocked and tilted. This means that every tanzanite is a blend of these pleochroic colors. The exact face-up color depends on the inherent color of the original rough, its size, the pleochroic colors the cutter favors when they orient the fashioned stone, and the light the finished gem is viewed  under. Cool lighting --like daylight equivalent fluorescent --will emphasize tanzanite's blue, while warm lighting --like incandescent --will make it appear more violet-to-purple.

Just like other colored gemstones, vivid strongly-colored tanzanites are highly sought after. Lighter toned pastel hues are more plentiful and affordable than vivid colors and have a subtle appeal of their own.

This 29.22-carat tanzanite has a deep violetish blue color sometimes described as midnight blue. - Courtesy Tanzanite Foundation ™ Source: GIA @topic:2


Title: Kunzite Journey of the Stone Abstract: This miner is handling a kunzite crystal at the Oceanview Mine in Pala, California, for the very first time since its formation. - Brendan Laurs

                      Few people outside the gem industry realize the true nature of a gemstone’s journey from the mine to the jewelry-store counter. Whether the gem is being offered to consumers at a traditional jewelry store, 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 bring a gem from mine to market. Source: GIA @topic:7


Title: Turquoise with Fingerprint Pattern Abstract: Figure 1. A few of the natural, untreated turquoise beads in this necklace display a fingerprint pattern. Photo by Don Mengason.

              The Carlsbad laboratory recently identified a natural, untreated turquoise bead necklace with an interesting feature. The bluish green beads displayed a natural turquoise structure with thin black matrix veining (figure 1). During microscopic examination, a few of the beads showed a less-saturated greenish discoloration pattern resembling fingerprints. The bead selected for testing had a spot RI of about 1.60 and fluoresced weak bluish green under long-wave UV, with no short-wave fluorescence. To rule out polymer impregnation treatment, we collected an infrared (FTIR) spectrum. It showed no peaks in the polymer regions, ruling out polymer-impregnated turquoise (K.S. Moe et al., “Polymer-impregnated turquoise,” Summer 2007 G&G, pp. 149–151). The unusual pattern may have been the result of glue or another contaminant present during the initial handling or drilling of the beads, preserving actual human fingerprints. With time and wear, the discoloration of the beads made the fingerprints more distinct (figure 2).

	Figure 2. The light area shows a discoloration in the form of a fingerprint pattern. Photo by Nathan Renfro.
Untreated turquoise is porous and often absorbs skin oils and other contaminants, making the color more greenish. As a result, turquoise is commonly treated to enhance its appearance and protect it from discoloration. Most of the product on the market, especially lower-quality material, has been wax- or polymer-impregnated to improve its durability (S.F. McClure et al., “Gemstone enhancement and its detection in the 2000s,” Fall 2010 G&G, pp. 218–240).
This interesting piece serves as a useful example of why turquoise is routinely treated. Simply handling it can affect the color and appearance over time, as illustrated by the fingerprint pattern preserved in this piece. Source: GIA @topic:11


Title: Turquoise with Simulated Matrix Abstract: Figure 1. A 78.60 ct greenish blue turquoise oval bead with
artificial metallic pyrite. The turquoise was filled with a mixture of crushed pyrite and polymer. Photo by C.D. Mengason.

	The Carlsbad laboratory recently examined a 78.60 ct greenish blue oval bead with patches that contained fragments of a metallic material in dark matrix (figure 1). Standard gemological testing of the greenish blue areas showed properties consistent with turquoise, including a refractive index of 1.60. Microscopic observations revealed the typical visual characteristics of turquoise: blue and white mottling, a granular texture, and a waxy luster with no evidence of dye. Raman analysis confirmed the metallic material was pyrite, and infrared spectroscopy indicated the greenish blue material was turquoise.

	Upon closer investigation using a standard gemological microscope, it became clear that the pyrite was composed of irregular and angular broken fragments suspended in a fine-grained black matrix. In addition, each dark patch displayed well-defined boundaries with hemispherical voids, presumably gas bubbles that had been cut through during polishing. Interestingly, one patch showed a discontinuity between two different shades of color and textures of the pyrite in black matrix (figure 2). Based on our observations, we believe these patches were formed by filling the cavities of the turquoise with a mixture of crushed pyrite crystals and a type of polymer resin. The treatment might have involved one or more filling episodes, which could explain the discontinuity seen in one of the patches. The filled turquoise was later polished into the finished product we observed.

	Figure 2. Closer magnification revealed crushed pyrite crystals, voids left behind from gas bubbles, and a discontinuity between two episodes of filling. Photo by Rebecca Tsang and Nathan Renfro; field of view 4.02 mm.

	In the past, we have seen a variety of treatments for turquoise, but this was the first example of an artificial pyrite-containing matrix examined at the Carlsbad laboratory. Source: GIA @topic:2


Title: Turquoise-Rock Crystal Composite Abstract: This 21.58 ct composite was found to have a top section of natural rock crystal and a base of natural turquoise. Photos by Gagan Choudhary.

Recently examined was a faceted rock crystal backed by a slice of turquoise—an obvious but unusual combination of gem materials. The 21.58 ct oval measured 20.02 × 15.03 × 9.05 mm and was easily identified as a composite due to its color and appearance. From the top, it appeared light greenish blue (see photo, left); from the sides, it exhibited a colorless top and bluish green slice at the base (right).
Further tests confirmed the specimen was made of rock crystal and turquoise, based on its colorless and greenish blue components. The colorless portion displayed an RI of 1.543–1.552, with birefringence of 0.009, while the greenish blue layer displayed a vague shadow edge at around 1.61. Under magnification, the colorless portion was clean and free of inclusions, while the greenish blue base showed some whitish cloudy patches, consistent with those in turquoise and similar materials. As expected, the junction plane contained numerous trapped, flattened gas bubbles without color. Under long- and short-wave UV light, a white to light yellowish glow was visible only along the junction plane, indicative of glue. Under a desk-model spectroscope, the specimen showed a weak absorption at about 430 nm.
FTIR spectra taken by orienting the colorless portion displayed peaks at approximately 3595, 3480, 3380, 3305, and 3198 cm–1—a pattern typically associated with natural rock crystal (e.g., Summer 2011 GNI, pp. 146–147). Raman analysis of the greenish blue base using a 532 nm laser in the 200–2000 cm–1 region revealed a strong peak at about 1040 cm–1, with a number of weaker peaks at approximately 238, 334, 427, 482, 554, 596, 645, and 810 cm–1. These peaks are consistent with those of turquoise in both the lab’s database and the RRUFF database of Raman spectra. No polymer-related peaks were present. In addition, qualitative energy-dispersive X-ray fluorescence (EDXRF) analysis revealed the presence of Al, P, Fe, and Cu, consistent with turquoise. As mentioned, a desk-model spectroscope revealed a weak absorption at around 430 nm, and the same was confirmed using UV-Vis spectroscopy, which displayed a sharp peak at approximately 429 nm (Fe3+) and a broad absorption at about 680 nm (Cu2+), suggesting natural rather than dyed color.
While analysis using both classical and spectroscopic techniques identified this as a composite of natural rock crystal and turquoise, the reason for its creation is still unclear. Source: GIA @topic:3


Title: Coated Tanzanite Abstract: Examination of 23 tanzanites coated by an apparently new technique revealed that the smaller stones (4–5 mm) could be identified as coated based on a combination of the unusually intense color and microscopic examination, which revealed surface iridescence as well as wear on facet junctions (small areas where the coating was abraded away). The two larger (3+ ct) stones did not show iridescence or wear, only small clues with high magnification, and therefore were much more difficult to identify. EDXRF and LA-ICP-MS analyses showed the presence of Co, Zn, Sn, and Pb in the coating. Source: GIA @topic:2


Title: Some Tanzanite Imitations Abstract: Since at least 1995, various materials have been manufactured to imitate tanzanite in the gem trade. These include two glasses, two different YAGs (yttrium aluminum garnet), and a synthetic corundum. These imitation tanzanites can be readily separated from the natural gem by standard gemological tests, such as refractive indices, optical character, specific gravity, UV-visible spectra, fluorescence, and the presence or absence of pleochroism. The identifications were confirmed by chemical analysis and Raman spectroscopy. Source: GIA @topic:1


Title: Chicken-Blood Stone from China Abstract: "Chicken-blood" stone is one of the most prized ornamental materials in China, especially for use in elaborate carvings and seals. A fine-grained mixture of dickite/kaolinite and quartz, with varying amounts of red cinnabar, chicken-blood stone is found in only two localities in China: Chunghua and Balinyouqi. This article describes this material and its gemological properties as well as the occurrence at the two known localities. Source: GIA @topic:12


Title: Book Review: Stories In Stone: The Enchanted Gem Carvings of Vasily Konovalenko Abstract: Stephen E. Nash and Richard M. Wicker, softcover, 304 pp., publ. by University of Colorado Press, Boulder, Colorado, 2016, $39.95.

	Vasily Konovalenko (1929–1989) was a Ukrainian-born artist who spent most of his career in Soviet Russia. His whimsical and charming figures, carved in stone, have delighted collectors and museum visitors alike. Stories in Stone, written by Stephen E. Nash, curator of archaeology at the Denver Museum of Nature and Science, gives the reader an in-depth look at the life of this passionate artist. Konovalenko often said, “One can learn to paint with stone.” And paint he did. Through his carving, he created small vignettes of life in the Soviet Union in which he grew up, focusing not on the political dogma that the government demanded from artists, but of the lives of ordinary people, often just village folk in their homemade birchbark shoes, enjoying a drink with friends, playing musical instruments, or ice fishing. Often humorous, and delightfully whimsical, Konovalenko’s characters come to life in his “paintings” in stone. Nash has interviewed Konovalenko’s widow and friends as well as museum academics, and he has researched archival documents for this book. He delves into the incredible journey of Konovalenko’s life, from his early days as a sculptor and set designer at the Donetsk Musical Theater and Stalin Theater for Opera and Ballet in Ukraine, to his successful career at the Mariinsky Theater in St. Petersburg. Nash tells stories of Konovalenko navigating the complex bureaucracy of Soviet Russian politics to bring his art to the public, and his eventual emigration to America in 1981.

	With a background in sculpture and set design, Vasily Konovalenko found an art form that ignited his artistic passion. While making a malachite box as a prop for a Mariinsky production of The Stone Flower, he fell in love with working in stone. The Stone Flower is a story of a young stonecutter Danila, and the trials he endures trying to woo his beloved Katerina with a beautiful stone flower he carves from malachite. Among the 20 Konovalenko sculptures on display at the Denver Museum of Nature and Science is a sculpture of Danila holding a malachite box. Nash states that Danila is “the totemic leader of all of Konovalenko’s sculptures,” perhaps representing Konovalenko himself. Danila, along with many other sculptures in this book, is photographed in great detail. The photographs show these sculptures close-up and from multiple views; as Nash points out, this is something not possible when viewing them in a display case. The reader can see the details of the young Danila’s face carved of Beloretsk quartz, the folds carved in his cacholong shirt with pearl buttons, and the brown jasper boots on a parquet floor, also made from pieces of jasper. The innocence and sincerity of Danila’s character is communicated with great sensitivity in Konovalenko’s carving.

	In “Sultry Midday,” he has created a scene of two heavyset women gossiping over bowls of soup and cups of tea as they sit bathing in a pool of water. Between them on a wood table is an intricately carved crystal samovar with a carved cacholong teapot. This theme of buxom, round-faced ladies gossiping over tea while bathing is repeated in “Twins.” Here, the charmingly ample-bodied women enjoy bathing in a pool of water created by agate edged by a ring of malachite. But this samovar is gold-plated silver with pastel cloisonné enamel decoration. An umbrella, also made of intricate cloisonné enamel patterns, shades the ladies, showing Konovalenko’s virtuosity in metalsmithing as well as stonework.

	His humorous creations include men as well. In “Sultry Afternoon 1,” he has created a portly man sitting in a pool of water eating a slice of watermelon. In “Sauna 1: The Thin and the Fat,” he shows a plump man on a table getting a massage from a skinny man; the juxtaposition between the two is quite humorous. Saunas have been very popular in Russia, and once a person had been in the warm steamy sauna, they emerged only to jump into ice-cold water. In “Walruses,” Konovalenko creates the illusion of a hole in a frozen pond by using layers of agate surrounded by snow made of calcite. Out of the hole pokes the head of a chubby woman wearing a red cap and an expression on her face that one can interpret only as “Brrr!” Standing outside on the ice is her husband, shirtless and wearing only a pair of shorts, boots, and a hat. Hunched over with his arms close to his sides and his hands clasped between his legs, he shivers in the cold winter air. These whimsical glimpses into the lives of everyday Russian people show not only the affinity the artist has for the subject, but also his wonderful sense of humor-- even when living under an oppressive government.

	Not all of Konovalenko’s work is humorous; he created some serious and emotionally powerful pieces, too. The sculptural group “Prisoners,” for example, shows two men dressed in prison uniforms made of black and white striped zebra jasper and building a wood shelter in the snow at their Siberian work camp. It was the norm in Stalin’s gulags that new prisoners would be forced to build their own barracks. On the back of each figure is a red target over where their heart would be, in case the order to shoot to kill was given. The red target, made of ruby, is the only bright color in this somber composition. Another moving sculpture is “Bereaved Mother,“ commissioned to commemorate the end of WWII. Here, a bereaved mother mourns over the Tomb of the Unknown Soldier. The dates 1941–1945 are carved into the tombstone, and white calcite flowers grow in a planter. It has a dark color palette, all set on a large, roughly cut piece of black obsidian. The scarf on the woman’s head is modeled jasper, emulating the colors of traditional Russian headscarves. Poignant pieces such as these show Konovalenko’s empathy for the suffering evident in his Soviet world, and are a strong contrast to the sculptures that show the simple joys of everyday life.

	In a chapter “Unfinished Business,” found toward the end of the book, the reader gets a glimpse into Konovalenko’s creative process through sketches of pieces that were never completed. The humorous and whimsical characters he is known for are here in vignettes such as “Family Bath,” which shows a mother and father with children all bathing in a large barrel, and another drawing of two “Gypsy Women Arguing.” His design skills are very evident in these drawings with rich bold colors and larger-than-life characters dressed in elaborate costumes. Konovalenko was always thinking of subjects and compositions he could sculpt, and what gems and minerals he could use to make them come to life.

Stories in Stone documents the life and work of an artist that is little known in America, even though he lived the last few years of his life here creating some of his most interesting pieces. As master set designer, enameler, metalsmith, and “painter in stone,” he has left a small part of himself in every piece. This book is a fitting tribute to Vasily Konovalenko and to his legacy to the Russian tradition of stone carving. This book would be of interest to anyone fascinated by sculpture, stone carving, and gemstones in general; those interested in 20th century Russian history and decorative arts would find Konovalenko’s life story and work particularly intriguing. Source: GIA @topic:6


Title: Pearl Description Abstract: Cultured pearls come in different sizes, shapes, and colors.

Perhaps the best-loved gems of all time, pearls—both natural and modern cultured pearls—occur in a wide variety of colors. The most familiar colors are white and cream (a light yellowish brown). Black, gray, and silver are also fairly common, but the palette of pearl colors extends to every hue. The main color, or bodycolor, is often modified by additional colors called overtones, which are typically pink (sometimes called rosé), green, purple, or blue. Some pearls also show the iridescent phenomenon known as orient.

This newly opened akoya pearl oyster reveals the cultured pearl that grew inside its gonad. This oyster’s scientific name is pinctada fucata (martensii).
Cultured pearls are popular for bead necklaces and bracelets, or mounted in solitaires, pairs, or clusters for use in earrings, rings, and pendants. Larger pearls with unusual shapes are popular with creative jewelry designers.

This multicolored necklace combines the beauty of Tahitian and South Sea cultured pearls. The scientific names of the oysters that produced them are, respectively, Pinctada margaritifera and Pinctada maxima. - Courtesy Frank Mastoloni & Sons, Inc.
Pearl—natural or cultured—is a US birthstone for June, together with alexandrite and moonstone.
Natural Pearls vs. Cultured Pearls
Natural Pearls
Natural pearls form in the bodies, or mantle tissue, of certain mollusks, usually around a microscopic irritant, and always without human help of any kind.
Cultured Pearls
The growth of cultured pearls requires human intervention and care. Today, most of the mollusks used in the culturing process are raised specifically for that purpose, although some wild mollusks are still collected and used.

This group of cultured pearls displays some of the exotic colors pearls can exhibit. - Blaire Beavers, courtesy Takayas Mizuno
To begin the process, a skilled technician takes mantle tissue from a sacrificed mollusk of the same species and inserts a shell bead along with a small piece of mantle tissue into a host mollusk’s gonad, or several pieces of mantle tissue without beads into a host mollusk’s mantle. If a bead is used, the mantle tissue grows and forms a sac around it and secretes nacre inward and onto the bead to eventually form a cultured pearl. If no bead is used, nacre forms around the individual implanted mantle tissue pieces. Workers tend the mollusks until the cultured pearls are harvested.
Pearl Types
There are four major types of cultured whole pearls:
Akoya Cultured Pearls
Akoya cultured pearls are the most familiar type of saltwater cultured pearl to most people in the U.S and other western markets. Many customers think of white or cream colored akoyas as the classic pearl used for jewelry, especially single-strand necklaces. Japan and China both produce akoya cultured pearls.
South Sea Cultured Pearls
Australia, Indonesia, and the Philippines are leading sources of these saltwater cultured pearls. South Sea cultured pearls can be white to silver or golden, depending on the type of oyster. Their large size and thick nacre, due to a long growth period, plus their limited critical growing conditions are all factors contributing to their value.
Tahitian Cultured Pearls
Cultivated primarily around the islands of French Polynesia (the most familiar of these is Tahiti). These saltwater cultured pearls, sometimes referred to as black pearls, have a wide color range. They might be gray, black or brown, and they can have blue, green, purple or pink overtones.
Freshwater Cultured Pearls
Freshwater cultured pearls are the most commonly produced pearls and they are one of the most popular pearl types among shoppers and jewelry designers. This is due to their remarkable range of sizes, shapes and colors, plus their commercial availability at lower price points. They are usually cultured in freshwater lakes and ponds, often with many pearls grown in one oyster. China is the leading source for freshwater cultured pearls.

Cultured pearls from Australia, Indonesia, the Philippines, and Myanmar, are grown in the Pinctada Maxima mollusk. This shell one is called gold-lipped because of the color of the outer rim of its mother-of-pearl layer.

The black-lipped mollusk can produce a variety of cultured pearl colors. The color of the mother-of-pearl layer is often related to the color of the resulting cultured pearl’s nacre. - Courtesy A & Z Pearls and Tasaki Shinju Co Source: GIA @topic:5


Title: Pearl Journey Abstract: Few people outside the gem industry realize the true nature of a cultured pearl’s journey from the producer 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.  Careful nurturing, countless hours of labor, and significant investment are needed to being a pearl to market. Source: GIA @topic:7


Title: Baroque Pearls Abstract: Figure 1. This hummingbird brooch features a 20.0 mm silver pink baroque pearl. It is surrounded by 319 diamonds (2.54 carats total), with a single 0.03 ct ruby eye mounted in 18K white gold. Photo by Robert Weldon/GIA, courtesy of Ron Greenidge and Emiko Pearls International.

Several vendors at this year’s Tucson gem shows, including AGTA and GJX, carried baroque pearls in an assortment of colors, sizes, and qualities. A common request from buyers was for pairs in larger sizes. The increased availability of less-expensive, quickly produced freshwater baroque cultured pearls from China in a wide range of sizes has had a noticeable impact on the market, as more designers are experimenting with them and more consumers are seeking them out. At the same time, sizable high-quality baroque pearls from the Philippines and Australia, particularly golden pearls, are becoming harder to find, as noted by AGTA exhibitor Ron Greenidge (Emiko Pearls International, Bellevue, Washington).

Emiko Pearls, founded in 1980, specializes in large and unusual classic and baroque pearls of gem and near-gem quality, namely South Sea, Tahitian, and “keshi” cultured pearls in golden, silver blue, gray, and pink hues. Greenidge showed us several examples of handmade jewelry that maximized the potential of exceptional baroque cultured pearls, particularly “jumbo” baroques in the 20–22 mm range. In response to market conditions, Emiko has transitioned over the past decade from offering loose pearls to almost exclusively producing finished goods.

Figure 2. The whimsical design of this octopus brooch accentuates the 17.3 mm gray
baroque Tahitian cultured pearl set in black-plated 18K gold. Also featured are 374 black
diamonds totaling 3.78 carats, 26 yellow diamonds totaling 0.33 carats, and 169 white
diamonds totaling 1.64 carats. Photo by Robert Weldon/GIA, courtesy of Ron Greenidge
and Emiko Pearls International.
Greenidge’s love of jewelry, paired with the increasing scarcity of high-quality larger pearls, has led the company to make one-of-a-kind pieces that showcase the uniqueness of individual pearls. Instead of finding pearls to place into existing jewelry, the firm designs jewelry around the pearl. The results are exquisite with whimsical and natural qualities, as seen in their hummingbird and octopus brooches (figures 1 and 2). Each piece is hand-welded from 18K gold, with diamonds and other precious stones added. The pieces, which take several months to create, are sought by clients in Asia and Europe (particularly China, Thailand, and Italy). High-end stores with one or two locations are the primary buyers, as Emiko does not mass-produce any of its designs. The swallow pin in figure 3, complete with forked tails, uses multiple keshi cultured pearls in two tones with matching diamond and gold colors.

Figure 3. This brooch depicting four swallows contains two golden “keshi” cultured pearls from the Philippines and two silver blue Australian South Sea keshi, ranging from 9 to 11 mm. They are surrounded by 211 yellow diamonds totaling 1.70 carats, 170 white diamonds totaling 1.23 carats, and eight ruby eyes totaling 0.28 carats, all set in white and yellow 18K gold. Photo by Robert Weldon/GIA, courtesy of Ron Greenidge and Emiko Pearls International.
As the consumption of pearls, including large baroque cultured material, increases with greater availability of lower-priced goods, expect to see other suppliers of high-quality pearls strive to differentiate themselves as Emiko has done. Source: GIA @topic:5


Title: Synthetic Diamond Articles from Gems & Gemology Abstract: When General Electric created the first gem-quality synthetic diamonds in 1971, the first place the company sent them after cutting was to GIA for examination and research. In the 44 years since then, GIA researchers have closely followed the development of laboratory-created diamonds – from those early experiments to the production of commercial quantities in the gem market. De Beers has conducted a robust research program on its own and has worked closely with GIA in this effort.

	The list of articles below chronicles GIA’s research efforts in this field to understand and identify synthetic diamonds. They are here for you to click, view and download.

Observations on CVD-Grown Synthetic Diamonds: A Review
By Sally Eaton-Magaña and James E. Shigley
	FALL 2016, VOLUME 52, NO. 3

Large Colorless HPHT Synthetic Diamonds from New Diamond Technology
By Ulrika F.S. D'Haenens-Johansson, Andrey Katrusha, Kyaw Soe Moe, Paul Johnson and Wuyi Wang
	FALL 2015, VOLUME 51, NO. 3

Near-Colorless HPHT Synthetic Diamonds from AOTC Group
By Ulrika F.S. D’Haenens-Johansson, Kyaw Soe Moe, Paul Johnson, Shun Yan Wong, Ren Lu, and Wuyi Wang
	SPRING 2014, VOLUME 50, NO. 1

Recent Advances in CVD Synthetic Diamond Quality
By Sally Eaton-Magaña and Ulrika F.S. D’Haenens-Johansson
	SUMMER 2012, VOLUME 48, NO. 2

CVD Synthetic Diamonds from Gemesis Corp
By Wuyi Wang, Ulrika F. S. D’Haenens-Johansson, Paul Johnson, Kyaw Soe Moe, Erica Emerson, Mark E. Newton, and Thomas M. Moses
	SUMMER 2012, VOLUME 48, NO. 2

Strongly Colored Pink CVD Lab-Grown Diamonds
By Wuyi Wang, and Patrick Doering, Joshua Tower, Ren Lu, Sally Eaton-Magaña, Paul Johnson, Erica Emerson, and Thomas M. Moses
	SPRING 2010, VOLUME 46, NO. 1

Latest-Generation CVD-Grown Synthetic Diamonds from Apollo Diamond Inc.
By Wuyi Wang, and Matthew S. Hall, Kyaw Soe Moe, Joshua Tower, and Thomas M. Moses
	WINTER 2007, VOLUME 43, NO. 4

Lab-Grown Colored Diamonds from Chatham Created Gems
By James E. Shigley, Shane F. McClure, Christopher M. Breeding, Andy Hsi-tien Shen, and Samuel M. Muhlmeister
	SUMMER 2004, VOLUME 40, NO. 2

Identification of Synthetic Diamond Grown Using Chemical Vapor Deposition (CVD)
By Philip M. Martineau, Simon C. Lawson, Andy J. Taylor, Samantha J. Quinn, and David J. F. Evans, and Michael J. Crowder
	SPRING 2004, VOLUME 40, NO. 1

Gemesis Laboratory-Created Diamonds
By James E. Shigley, Reza Abbaschian, and Carter Clarke
	WINTER 2002, VOLUME 38, NO. 4

A Chart for the Separation of Natural and Synthetic Diamonds
By James E. Shigley, Emmanuel Fritsch, and Ilene Reinitz, Thomas M. Moses
	WINTER 1995, VOLUME 31, NO. 4

The Gemological Properties of Russian Gem-Quality Synthetic Yellow Diamonds
By James E. Shigley, Emmanuel Fritsch, John I. Koivula, Nikolai V. Sobolev, and Igor Y. Malinovsky, and Yuri N. Pal’ yanov
	WINTER 1993, VOLUME 29, NO. 4

De Beers Near Colorless-to-Blue Experimental Gem-Quality Synthetic Diamonds
By Marie-Line T. Rooney, C. M. Welbourn, James E. Shigley, Emmanuel Fritsch, and Ilene Reinitz
	SPRING 1993, VOLUME 29, NO. 1

The Gemological Properties of the De Beers Gem-Quality Synthetic Diamonds
By James E. Shigley, Emmanuel Fritsch, Carol M. Stockton, John I. Koivula, C. W. Fryer, Robert E. Kane, and David R. Hargett, Clayton W. Welch
	WINTER 1987, VOLUME 23, NO. 4

The Gemological Properties of the Sumitomo Gem-Quality Synthetic Yellow Diamonds
By James E. Shigley, Emmanuel Fritsch, Carol M. Stockton, John I. Koivula, and Charles W. Fryer, and Robert E. Kane
	WINTER 1986, VOLUME 22, NO. 4 Source: GIA @topic:4


Title: An Era of Sweeping Change in Diamond and Colored Stone Production Markets Abstract: The diamond, colored stone, and pearl businesses have witnessed unprecedented change since the turn of the 21st century. Not only have new markets for gems emerged around the world, but channels of distribution have also changed dramatically as a result of economic forces and political pressures. De Beers abandoned its single-channel seller role, which created —for the first time in over a century—a competitive rough diamond market. Political problems in Madagascar and a ban on gem exports from Myanmar disrupted supply channels for sapphire and ruby. And the proliferation of new sales avenues, through the Internet and TV, has given consumers much more information about gems and forever changed the way they buy them. The use of gems to subsidize bloody conflicts and repressive regimes has moved the trades to become more accountable, as concerns over terrorism and illicit trading have created a new legal environment. At the same time, a new class of consumers who value ethically, socially, and environmentally friendly products are making their demands known in the gemstone business. Source: GIA @topic:9


Title: Internal Structures of Natural Pearls from Pinctada maxima, Identification of Resin-Filled Turquoise, Spinel Inclusions Chart, and More…… Abstract: Spring ushers in a feeling of renewal, and as we start to slowly recover from the global pandemic, it is a welcome sentiment. Join us as we investigate the inner structures of natural Pinctada maxima pearls, the technical evolution of turquoise treatments using resin filling, and a mathematical approach to predicting color in uniaxial gemstones. Even though the Tucson gem shows were canceled this February, we are able to offer more than 20 pages of captivating interviews covering how many in the trade have been weathering the situation along the entire supply chain.

“A mathematical method using visible spectroscopy to accurately predict color, the most important quality for a colored gemstone…”

Natural Pinctada maxima pearls take center stage in the lead article as Artitaya Homkrajae and fellow GIA researchers conduct a detailed analysis of 774 natural pearls collected from wild marine mollusks. These pearls were classified into six broad internal structural types based on X-ray techniques such as real-time microradiography (RTX) and X-ray computed microtomography (μ-CT). The results of this work support the efforts to aid in the dependable identification of natural versus cultured pearls by gemological laboratories.

In the second article, Ling Liu and a team from the Gemmological Institute, China University of Geosciences in Wuhan use ultraviolet fluorescence, spectrofluorometry, and Fourier-transform infrared (FTIR) spectrometry to characterize resin-filled turquoise. Their research addresses an urgent need to detect the prevalence and constantly evolving treatment techniques applied to turquoise sourced from China’s Hubei Province.

Next, Che Shen and coauthors provide a mathematical method using visible spectroscopy to accurately predict color, the most important quality for a colored gemstone, and guidance on cutting backed by science. This comprehensive study predicts the color of a uniaxial gem when viewed in any direction by reconstructing unpolarized spectra provided the polarized spectra and relative viewing angle to the c-axis are known.

In our last article, Nathan Renfro and coauthors present a beautiful array of inclusions in natural, treated, and synthetic spinel, as well as inclusions of spinel in other gemstones. Their colorful spinel inclusions chart is enclosed with every printed copy of this issue. Laminated versions of it, along with the five inclusion charts, are also available at store.gia.edu.

As always, interesting gemological findings abound in our regular sections. Discover natural diamonds displaying asterism and bicolor rough diamond crystals featuring distinct colorless and pink areas in Lab Notes, while Micro-World delights with a glimpse into the inner landscapes of gems: a kaleidoscopic play of interference colors seen in thin-film fluid inclusions in aquamarine and a cloud inclusion shaped like a diamond profile mimicking its diamond host. The Gem News International section features a virtual report on the pandemic’s impact and how the trade adapted their business practices to continue to flourish, as well as the headline-grabbing Cookie Monster geode and a glance back in time at hand-drilled holes in diamond briolettes. This issue also contains the annual G&G Challenge, where you can test your gemological knowledge of our 2020 issues. Finally, be sure to see our announcement of the Dr. Edward J. Gübelin Most Valuable Article Award winners.

We hope you enjoy the Spring 2021 edition of Gems & Gemology!

Duncan Pay | Editor-in-Chief | dpay@gia.edu Source: GIA @topic:5


Title: Colored Stones Cut with High Precision Abstract: Figure 1. Tiny but precisely cut and highly saturated stones were offered at Tucson. Photo by Eric Welch.

              At the AGTA and GJX shows, China Stone (Bangkok) marketed a selection of tiny, precisely cut natural gemstones. Sold as parcels, the stones ranged from 0.03 to 3.0 mm in diameter. Despite their small size, they were impressively saturated with a full spectrum of colors (figure 6).

The stones are natural and purchased directly from the source suppliers, then cut and polished in the company’s Chinese factories. With computer-controlled automation, the stones are digitally calibrated and precisely cut to be set into commercial jewelry. The company’s products include ruby, blue and fancy-color sapphire, amethyst, chrome tourmaline, and tsavorite. The matched stones can be used in graphic designs or as accent stones in fine jewelry.

Clients of China Stone’s high-precision cut stones include watch manufacturers, fine jewelers, and designers. The company developed its own inventory grading, stock management, and order processing systems to maintain the strictest standards of shape, size, color, and quality. For each type of gemstone, color grades are assigned with several different color codes. Customers can easily combine their favorite colors and sizes of a certain stone type and see whether the goods are in stock or need to be ordered. With the development of automated cutting technology, small rough can be easily handled and cut with very high precision, giving jewelry designers creative flexibility. Source: GIA @topic:7


Title: Impregnated and Dyed Turquoise Abstract: Figure 1. Spectroscopic analysis of this 15.21 gram turquoise reveals that the material has been both impregnated and dyed. Photo by Wen Han.

Turquoise has a cryptocrystalline structure, which gives rise to the gem’s porosity. Its vulnerability to body oils, ordinary solvents, and dirt can induce variation of color. This porous gemstone’s appearance and durability can be enhanced by various treatment techniques, such as dyeing, impregnation (with polymer, wax, or plastic), and the proprietary Zachery process (E. Fritsch et al., “The identification of Zachery-treated turquoise,” Spring 1999 G&G, pp. 4–16).

Turquoise, often featured in vintage jewelry pieces, is becoming increasingly popular in the Chinese market. Recently, the NGTC Beijing lab received for identification a 15.21 gram turquoise sphere with green color (figure 1). The specimen measured approximately 3.5 cm in diameter; its spot refractive index value was 1.59 and its hydrostatic specific gravity value was 2.58. The test sample was inert, except for several lines and a cavity with moderate white fluorescence under both long-wave and short-wave UV radiation (figure 2), suggesting impregnation. Magnification showed some filling materials were also present in the cavities. Additionally, green color concentration was observed in the material’s cavities and cracks.

Figure 2. Some lines, along with the cavity, fluoresce white when exposed to long-wave
UV radiation, indicating the presence of filling material. Photo by Wen Han.
Infrared reflectance spectroscopy revealed complicated peaks containing turquoise and impregnated materials. The bands at 1118 and 1050 cm–1 were assigned to the asymmetric stretching vibrations of phosphate units, while the 835 cm–1 was caused by the bending vibration of OH units. Other features from approximately 647 to 482 cm–1 were due to the phosphate bending modes of turquoise. The 2918 and 2850 cm–1 peaks were attributed to wax; additionally, a series of small peaks from 1800 to 1350 cm–1 indicated the presence of organic matter. To identify this organic material, we scraped off some powder from the edge of one of the cavities with a blade. The resulting infrared transmittance spectrum indicated the presence of three kinds of polymer (figure 3). The 1731 and 1013 cm–1 peaks were attributed to acrylic polymer, and the 1611 and 1510 cm–1 peaks were due to epoxy resin; both are commonly applied to various gem materials for impregnation. Peaks at 1410, 1260, and 797 cm–1 were characteristic absorption features of silicone. Silicones are polymers consisting of repeating units of siloxane (a functional group composed of two silicon atoms and one oxygen atom, often combined with carbon and hydrogen). The 1410 and 1260 cm–1 peaks were caused by asymmetric and symmetric deformation vibrations of Si-CH3, respectively, and the 797 cm–1 was assigned to the Si-C stretching vibrations of the silicones.

Figure 3. The infrared transmittance spectrum of small amounts of powder scraped from
the sample shows that the turquoise was impregnated with three components: epoxy resin,
acrylic polymer, and silicone.
EDXRF chemical analysis detected mainly P, Al, Cu, Fe, and Si. The first four are consistent with the chemical composition of turquoise, while Si was suspected to be a byproduct of silicone impregnation. The UV-Vis spectrum showed two absorption bands: a band centered at about 428 nm caused by Fe3+ d-d electronic transition, and a sharp band centered at approximately 677 nm (figure 4). Natural-color turquoise does not show the 677 nm band; many Chinese labs consider this feature characteristic of dyed material.

Figure 4. When compared with the spectrum of a known natural turquoise sample, the
677 nm band of the UV-VIS spectrum indicates that the sample in this study was dyed.
Turquoise is usually impregnated with acrylic polymer or epoxy resin for stabilization in addition to the dyeing process to change its color. This is the first time we have encountered turquoise that was dyed and impregnated with three components. Our investigation reinforces the need to identify any and all treatments. Source: GIA @topic:11


Title: Robotic Colored Stone Cutting Machines Abstract: Figure 1. Kiwon Jang checks a cassette of stones during the Jang 1024’s robotic cutting process. Photo by Tao Hsu.

	At the technology pavilion of the AGTA show, master cutter Kiwon Jang of KLM Technology (New Brunswick, New Jersey) demonstrated the Jang 1024, a robotic system for cutting colored stones (figure 1).

	KLM provides cutting services to the gem trade. Mr. Jang began his career working with cubic zirconia in his native Korea. Since moving to the United States 30 years ago, he has developed multiple systems for automatic gem cutting, with 10 systems in KLM’s New Jersey factory. The company also sells the machine to overseas clients and provides on-site training for the systems. G&G previously reported on one of his compact machines (Fall 2012 GNI, p. 233).

	The Jang 1024 is his most recent product. The machine’s process is controlled by a computer installed with designing and cutting software written by Mr. Jang. The water-cooled system (figure 2) is designed for mass production; depending on stone size, it can handle up to 56 melee at a time (figure 3). The machine can produce a round brilliant cut from 1 to 30 mm, while the largest size for emerald cuts is 25 mm. According to Mr. Jang, the maximum tolerance the machine can accommodate is 0.05 mm. The daily capacity of this machine is 2,000–4,000 melee between 1.0 and 3.0 mm, 400–800 stones between 3.5 and 10.0 mm, or 100–200 stones larger than 10.0 mm. Aside from periodically checking the stones, the entire process from preforming to polishing is done by the computer. Mr. Jang informed us that the majority of his clients are miners and cutting factories in Brazil and Russia, along with many African countries. Most of his customers in the United States are domestic dealers seeking fast local service.

Figure 2. A cassette of stones is cut using water as a cooling agent. Photo by Tao Hsu.

Figure 3. A cassette of stones is cut using water as a cooling agent. Photo by Tao Hsu. Source: GIA @topic:7


Title: A Variety of Colored Stones from Mayer & Watt Abstract: Figure 1. An 8 mm 2.01 ct trillion-cut gray spinel from Myanmar. Photo courtesy of Mayer & Watt.

Mother-and-son team Laurie and Geoffrey Watt (Mayer & Watt, Maysville, Kentucky) noted that while there were plenty of customers at the AGTA show this year, the formula for success was a wide selection of materials and competitive pricing. Their booth had a selection of what was hot this year: the highly sought-after gray zircon, as well as pink and blue zircon; fancy colors of Montana sapphire; Ethiopian emerald from Shakiso; electric pink spinel from the Mahenge deposit in Tanzania; and a wide variety of garnet colors, such as true purple garnet from Mozambique. Gray spinel was one of the most popular stones this year for a wide variety of jewelry applications, including engagement rings. Mayer & Watt had one of the best selections of actual achromatic gray spinel, with no stray hues of blue, green, or purple (figure 1). The true purple garnet offered by Mayer & Watt and a handful of other vendors at AGTA and GJX comes from a single small source discovered in 2015 in Mozambique (figure 2). This garnet lacks a pinkish cast, unlike less expensive pinkish purple material coming from Tanzania.

Figure 2. This purple garnet from Mozambique is a 1.25 ct hexagon measuring 6.1 mm. Photo courtesy of Mayer & Watt. Source: GIA @topic:1