# Publication Year: 2013
# Title: Three CVD Synthetic Diamonds Submitted to Mumbai Laboratory
# Abstract: CVD-grown synthetic diamonds continue to become more abundant in the gem market, as evidenced by several reports from major diamond-grading laboratories during the past year (e.g., C. Even-Zohar, “Synthetics specifically ‘made to defraud,’” Diamond Intelligence Briefs, Vol. 27, No. 709, 2012, pp. 7281–7283). In December 2012, three CVD synthetic diamonds were submitted to GIA’s Mumbai laboratory. In keeping with the evolving technology of the CVD process, the gemological and spectroscopic characteristics of these type IIa synthetic diamonds suggested that they experienced different growth and/or treatment histories.

One sample was a 0.93 ct very light brown (O to P range) rectangular step cut with a VVS2 clarity grade due to the presence of pinpoint inclusions and graining. Viewed under crossedpolarizers it showed heavy strain, with high-order birefringence colors. The photoluminescence (PL) spectra acquired at liquid-nitrogen temperatures using various laser excitations were dominated by the emission of [N-V]0 and [N-V]– centers (with zerophonon lines at 575 and 637 nm, respectively). These ZPLs are widened by high levels of strain and have been previously studied in CVD synthetic diamonds (W. Wang et al., “CVD synthetic diamonds from Gemesis Corp.,” Summer 2012 G&G, pp. 80–97). The [N-V]0/– peaks for this sample had full-widths at half-maximum (FWHM) of 0.43 nm and 0.35 nm, respectively. These are relatively broad compared to colorless diamonds, but consistent with the high strain observed under crossed polarizers. The 596.5/597.2 nm doublet commonly observed in “as-grown” CVD synthetic diamonds was weak, as was the 736.5/736.9 nm doublet attributed to [Si-V]–. Notably, the [Si-V]– emission was too weak to detect with the 514.5 nm laser excitation. Infrared laser excitation at 830 nm resulted in many emission peaks in the 850–880 nm region, dominated by a sharp peak at 878.5 nm whose origin has not been conclusively identified. The DiamondView fluorescence was primarily red due to the strong [N-V] centers. Although CVD-characteristic violet-blue dislocation patterns were observed, growth striations could not be discerned (figure 1A). The sample did not phosphoresce. The PL features observed, the [N-V]0/– widths, and the DiamondView behavior were similar to those reported for near-colorless CVD synthetics produced by Apollo, Inc. (e.g., W. Wang et al., “Latest-generation CVD grown synthetic diamonds from Apollo Diamond Inc.,” Winter 2007 G&G, pp. 294–312).

Figure 1. DiamondView fluorescence images show distinct colors and patterns that helped identify these as CVD synthetic diamonds. Red fluorescence with purple mottling appears in the putative “as-grown” O-P color rectangular step cut (A). The greenish blue striations in the 0.52 ct sample are more typical patterns (B). The 0.57 ct CVD synthetic demonstrates a unique combination of fluorescence features—dominant [N-V] center–related fluorescence, with minor areas showing some violet-blue dislocations and greenish blue striations (C–D). [Image A by S. Magana, images B–D by U. D’Haenens-Johansson]
The other two samples were round brilliants weighing 0.52 and 0.57 ct. Both received G color and VS1 clarity grades. The clarity grades were affected by pinpoint inclusions and small fractures. Both round brilliants were weakly strained, revealing loworder (gray and brown) interference colors. They shared several PL spectroscopic traits, including emissions from [N-V]0/–, [Si-V]–, H3 (503.2 nm), and weak N3 (415.2 nm) centers. The 596.5/597.2 nm doublet was not observed in either specimen. The absence of this feature, combined with the presence of multi-nitrogen defects such as H3 and N3, suggests that they had undergone post-growth high-temperature annealing to remove the asgrown brown coloration (again, see W. Wang et al., 2012). The FWHMs for the [N-V]0 and [N-V]– centers were 0.21 nm and 0.16 nm, respectively, for the 0.52 ct round, and 0.23 nm and 0.22 nm for the 0.57 ct sample. These were comparable to the narrowest widths reported for natural diamonds and newer-generation HPHT-treated CVD synthetics produced by Gemesis Corp., and consistent with the low levels of strain detected.

The round brilliants exhibited distinct behavior when examined using the DiamondView instrument (see figure 1, B–D). The 0.52 ct sample showed greenish blue fluorescence and clear growth striations, as well as strong green-blue phosphorescence. These observations were akin to those for HPHT-treated CVD synthetic diamonds produced by Gemesis (again, see W. Wang et al., 2012). Although green-blue phosphorescence was also observed for the 0.57 ct sample, its DiamondView fluorescence images were primarily purplish pink, with violet-blue dislocation bundles and a patch of greenish blue fluorescence. This fluorescence combination in a CVD synthetic diamond had never been observed at a GIA laboratory. The purplish pink fluorescence color was attributed to [N-V] centers. Comparison of the Raman normalized PL intensities of the peaks revealed that the [N-V]0 and [N-V]– peaks were approximately 57% and 68% more intense in the 0.57 ct round than in the 0.52 ct sample. This may explain the difference in the DiamondView fluorescence responses of these synthetic diamonds. It is possible that the 0.57 ct round was HPHT annealed at a lower temperature.

The gemological and spectroscopic observations for these three samples emphasize the variations that might be possible through different growth procedures and subsequent treatment for near-colorless to lightl brown CVD synthetic diamonds. Nevertheless, the specimens could be readily identified as synthetic by careful analysis of data from a combination of laboratory techniques. @chapter:9 @chapter:1 @chapter:9


# Publication Year: 2001
# Title: Ammolite: Iridescent Fossilized Ammonite from Southern Alberta, Canada
# Abstract: A relative newcomer to the world gem market (since the 1960s), Ammolite is a form of aragonite that is obtained from vivid iridescent fossilized ammonite shells mined in Alberta, Canada. The gem material, from the extinct species Placenticeras meeki and P. intercalare, is found only in certain horizons of the Bearpaw Formation of  Late Cretaceous age (about 70–75 million years old). Because the iridescent layer is generally thin and fragile, most Ammolite is fashioned into assembled stones. This article describes the history of Ammolite as a gem material and the geologic setting of the main producing mines; offers an explanation for the formation of Ammolite and the origin of its color (i.e., iridescence caused by an interference phenomenon); presents production data, gemological properties, and a grading classification; and describes the manufacturing process. @chapter:1 @chapter:0 @chapter:1


# Publication Year: 2014
# Title: Supporting the Researchers of Tomorrow
# Abstract: In our recent print issues, you’ve likely noticed an ad on the journal’s inside cover promoting postdoctoral research opportunities. This is part of a GIA initiative to attract new research scientists. We recognize that sustaining future research is fundamental to all of GIA’s core gemological laboratory and education services that support the industry and our mission to safeguard consumers.

As part of this effort, we’re delighted to announce that GIA will be the principal sponsor of the International Diamond School (IDS), to be held January 27–31 in Brixen, Italy. The school will be led by three leading diamond geoscientists: Fabrizio Nestola of the University of Padova, Italy; Steven Shirey of the Carnegie Institution in Washington, DC; and Graham Pearson of the University of Alberta, Canada. The school brings together leading academics and practicing members of the diamond geoscience community—including our own Dr. Wuyi Wang—with the next generation of postdoctoral and masters-level researchers. It’s a fantastic opportunity for attendees to network with the leaders in diamond exploration, advanced research-level analysis, diamond morphology, inclusion chemistry, and geologic occurrences in a way that will inspire their future studies. GIA’s contribution will directly benefit these up-and-coming research scientists by reducing the attendance fees for the conference. The IDS website is at http://www.indimedea.eu/diamond_school_2015.htm

Our lead article in this edition, a collaboration between GIA and Sri Lankan authors, presents an illuminating survey of Sri Lanka’s gem and jewelry industry based on firsthand visits to mining, cutting, jewelry manufacturing, and retail centers. They document a revitalized industry that’s blending hard-won traditional skills with innovative strategies and technologies to gain a stronger presence in global markets.

Our second paper, by Nicholas Sturman and his colleagues from GIA’s Bangkok laboratory, provides a gemological characterization of 22 non-nacreous pen pearls. This study reveals not only the porcelaneous nature of these pearls, but also the unusual beauty of their surface textures and inner structures.

Next, noted author and corundum expert Richard Hughes delves into a basic gemological property: pleochroism. His intriguing paper—aimed at practicing gemologists as much as researchers—examines this property’s impact on the appearance of faceted gems and looks to demonstrate that pleochroism is always visible to some degree, even when viewing a gem along an optic axis.

In the final article, Dr. Zuowei Yin from the China University of Geosciences in Wuhan heads a study of pale-colored nephrite jade from a new deposit in Guangxi Province with interesting banded or dendritic patterns.

In addition to the four feature articles, you’ll find our regular Lab Notes and Gem News International sections, along with the winners of the 2014 G&G Challenge.

For all our print subscribers: You’ll notice that your copy of journal was delivered inside a new recyclable (polyhydroxyalkanoate, or PLA) wrapper. We’d like to thank Dr. George Rossman of G&G’s editorial review board for this suggestion.

Please enjoy the Fall 2014 edition! @chapter:21 @chapter:1 @chapter:21


# Publication Year: -
# Title: Spotlight on Gemology at the Geological Society of America Annual Conference
# Abstract: Visitors to GIA’s booth at the 2014 GSA conference spoke with representatives, including Dr. James Shigley, left, to learn about GIA, gemology education programs and career opportunities. Photo by Cathy Jonathon/GIA

                      Diamonds and colored gems have captivated people with their rarity and beauty for thousands of years.

But for GIA’s research team and other geoscientists who attended the Geological Society of America’s (GSA) annual meeting, it’s the science of gems that’s most fascinating.

The conference is one of the most respected in the geological science community and draws top researchers and noted academics – representing more than 50 countries – from around the world.

“It’s the meeting geoscience professionals and students attend,” Dr. James Shigley, GIA’s distinguished research fellow, said. In fact, nearly 40% of the roughly 6,700 attendees were undergraduate and graduate geoscience students.

“This conference enables the Institute to reach a new audience and share our research with other members of the scientific community,” he said. “It also provides an opportunity to expose geology students to gemology. We spoke with many who were interested in education programs and job opportunities at GIA in the geosciences field.”

Recognition of gemology as a field in the geosciences has increased in recent years, but many visitors to GIA’s booth were unfamiliar with the Institute, Shigley said.

“Our presence at the conference gave visitors the opportunity to learn more about who we are, what we do and the types of gemology positions available,” he added. “It was a chance for a face-to-face conversation with GIA researchers.”

Held Oct. 19-22 in Vancouver, British Columbia, Canada, the 2014 GSA conference included 346 technical sessions and 4,487 oral or poster presentations. Each half-day session was made up of brief presentations – on a related theme – by numerous professionals and students. GIA has had a booth at the conference for many years, but last year, the 125th anniversary of GSA, marked the first time the Institute hosted a half-day session. This year, GIA hosted back-to-back sessions – a full day of presentations.

GIA’s presentations emphasized the science of gems, including exploration, documenting the conditions of formation and characterizing the properties of gem minerals, and improving gem identification techniques. The sessions, titled “Gemological Research in the 21st Century: Exploration, Geology and Characterization of Diamonds and Other Gem Minerals,” included presentations from key GIA researchers including Dr. Wuyi Wang, Dr. Mike Breeding, Troy Ardon, along with Dr. Aaron Palke and Dr. Karen Smit, both postdoctoral research associates at GIA, as well as other renowned researchers and professionals in the geoscience community.

Shigley and Dona Dirlam, GIA’s director of the Richard T. Liddicoat Gemological Library and Information Center, moderated the presentations.

In addition to the sessions, GIA also hosted four gemological poster presentations on topics of Columbian emeralds, diamond inclusions and Sowerby’s “British Mineralogy,” illustrated volumes from the early 1800s. Each presenter, or group of presenters, created a poster of their research and were available to field questions from interested attendees.

GIA’s Vancouver alumni chapter hosted an event for local alumni to meet with researchers and speakers from the conference. More than 50 people gathered for the dinner reception on Oct. 20.

Dirlam, who has been involved with the GSA conference since 1980, understands the importance the meeting has to the scientific community and has been instrumental in GIA’s participation over the years. Not only is it important for GIA to learn about advancements in the geosciences, but it provides a forum to share gemological research, she said.

“Our involvement at this conference exposes the audience to what GIA researchers are doing day in and day out,” Dirlam said. @chapter:21 @chapter:0 @chapter:21


# Publication Year: 2015
# Title: Large Star Emerald
# Abstract: Figure 1. A weak, six-rayed star is visible in this 25.86 ct emerald cabochon. Photo by Robert Weldon/GIA, courtesy of Manuel Marcial de Gomar.

	Star emeralds are rare specimens, and most are found in either Brazil or Madagascar. In 1999, Manuel Marcial de Gomar (Key West, Florida) purchased a 1,000-carat parcel of rough emeralds from Diallo Mahmoud, an independent emerald dealer based in Africa. Mahmoud noted that the parcel came from Madagascar. Marcial de Gomar later noticed that some crystals showed indications of chatoyancy. He chose this particular piece thinking it could be cut to produce a cat’s-eye emerald. Miami-based cutter Jone Ribeiro cut the stone into a 25.86 ct double cabochon (figure 1). Marcial de Gomar put the stone into his personal collection, where it stayed for 13 years, until independent gemologist and appraiser Martin Fuller examined Marcial de Gomar’s collection in 2013. Both experts recognized that this emerald was a star and not a cat’s eye. It was subsequently sent to GIA’s Carlsbad laboratory for an identification report.

Figure 2. Minute fluid inclusions oriented parallel to the basal plane of the crystal are the cause of this emerald’s asterism. The inclusions exhibit thin-film interference, causing rainbow colors that are visible at high magnification. Photo by Nathan Renfro; field of view 1.8 mm. Courtesy of Manuel Marcial de Gomar.

	The stone is described as an oval double cabochon natural star emerald. The asterism was caused by minute hexagonal fluid inclusions oriented parallel to the basal plane of the crystal (e.g., Spring 2004 GNI, p. 104; K. Schmetzer, et al., “Asterism in beryl, aquamarine, and emerald—an update,” Journal of Gemmology, Vol. 29, No. 2, 2004, pp. 66–71). They exhibit thin film interference with direct, pinpointed light that caused the asterism, as well as rainbow colors seen at high magnification (figure 2). Prior to this report, very few asteriated emeralds were recorded (e.g. Fall 1995 GNI, p. 206; Spring 1995 GNI, pp. 60–61; Spring 2002 GNI, p. 104; Summer 2006 GNI, pp. 171–172). This is the eleventh, and largest, star emerald known to date. @chapter:19 @chapter:0 @chapter:19


# Publication Year: 2014
# Title: Books: Jewels by JAR
# Abstract: Essay by Adrian Sassoon, 144 pp., illus., publ. by the Metropolitan Museum of Art, distributed by Yale University Press, New Haven and London 2013, US$40.00. The JAR butterfly brooch (1994) is from a private collection. Photograph by Katharina Faerber, courtesy of JAR, Paris.

              Joel Arthur Rosenthal is not a household name. Yet to many in the jewelry industry, the designs he creates for his jewelry house, JAR, are legendary for their innovation and artful use of color. Established in 1978, JAR is synonymous with quality and style. Alongside business partner Pierre Jeannet, Rosenthal has built a firm whose reputation is rooted in beauty, discretion, attention to detail, and deeply personalized service. Jewels by JAR was created to accompany the retrospective of the same name at the Metropolitan Museum of Art in New York City.

The book opens with a dedication by Rosenthal himself, with a foreword by Thomas P. Campbell, director of the Metropolitan. The main text is an engrossing essay by art dealer Adrian Sassoon on Rosenthal’s career. The essay will be particularly interesting to followers of the notoriously publicity-shy Rosenthal.

The remainder of the book consists of page after page of fabulous color images depicting handcrafted JAR creations. While one finds copious amounts of luxurious gems, gold, and platinum in his jewelry, Rosenthal has never limited his creations to so-called precious materials. Materials such as beetle wings, wood, resin, enamel, bronze, and aluminum have been used to complete his artistic vision. The success he has achieved is obvious in each photograph, deepening this reader’s lament that she did not have the opportunity to view the exhibit in person.

Even the pieces’ presentation boxes do not escape the discriminating eye of the designer. The interior of a given box might be custom-lined with suede of a color meant to complement the jewel it will hold. Box lids are often embossed with the owner’s initials, serving as a reminder that each JAR creation is indeed one-of-a-kind.

Truly lovely to look at, with an interesting text, Jewels by JAR is a “must-read,” not only for serious collectors of Rosenthal’s work, but for anyone interested in jewelry and jewelry design. @chapter:20 @chapter:2 @chapter:20


# Publication Year: 2023
# Title: Trends in Israel's Diamond Trade in the First Seven Months of 2023
# Abstract: The Diamond Supervisor, under the Ministry of Economy and Industry of Israel, has released a summary report for July 2566, indicating a negative trend in the global diamond industry and specifically in Israel, which has been affected since the conflict in Ukraine. During the first seven months of 2566, diamond trade in Israel remained in decline, with both major categories of products experiencing a reduction in trade value.
The overview of imports and exports during the first seven months of 2566 for rough diamonds (raw and polished) is as follows:
Net imports of rough diamonds to Israel totaled approximately 661 million USD, a decrease of 45% compared to the same period last year. Net imports in July 2566 alone dropped by about 46% compared to July 2565.
Net exports of rough diamonds during the same period totaled about 515 million USD, marking a significant decline of 53% compared to the first seven months of 2565. In July 2566, net exports of rough diamonds decreased by 44% compared to July of the previous year.
Net imports of polished diamonds during the first seven months of the year totaled about 1.57 billion USD, a decrease of 24% compared to the same period in 2565. In July 2566 alone, net imports of polished diamonds decreased by approximately 34% compared to July of the previous year.
Net exports of polished diamonds totaled about 1.9 billion USD, a decrease of 25% compared to the same period in 2565. In July 2566, net exports of polished diamonds decreased by about 31% compared to July of the previous year. @chapter:37 @chapter:3 @chapter:37


# Publication Year: 2019
# Title: Dislocation Chain in Oregon Sunstone
# Abstract: This orangy red Oregon sunstone contained an interesting decorated dislocation that was visible using fiber-optic illumination. Photomicrograph by Jessa Rizzo; field of view 4.79 mm.

The author recently examined a high-quality faceted orangy red Oregon sunstone weighing 6.77 ct. Examined under magnification with fiber-optic illumination, the stone displayed an unusual inclusion that consisted of a decorated dislocation string (see above). Copper exsolution platelets, which are common in Oregon sunstone, were also observed. In this example, the decorated dislocation followed a rectangular pattern, consistent with the crystal structure of the host feldspar. This unique light-scattering dislocation chain is the first that the author has encountered in Oregon sunstone. @chapter:26 @chapter:0 @chapter:26


# Publication Year: 1994
# Title: Color Grading of Colored Diamonds in the GIA Gem Trade Laboratory
# Abstract: The GIA Gem Trade Laboratory (GIA GTL) presents the system it uses to color grade faceted colored diamonds, and the information on which it is based. This system involves a trained grader establishing the characteristic color in a standardized illumination and viewing environment, using various reference materials for color comparison. Here, the Munsell color system is used to illustrate the relationships between the different color terms used. GIA GTL "Fancy grade" nomenclature for colored diamonds has been expanded to better address all colors. This color terminology will soon be incorporated into a new GIA GTL colored diamond report. @chapter:41 @chapter:1 @chapter:41


# Publication Year: -
# Title: Gems & Gemology’s 7 Most Unusual Encounters from 2019
# Abstract: Face-up image of the natural diamond with CVD synthetic diamond overgrowth. The blue color is due to the boron-doped CVD layer. Photo by Robison McMurtry

Each year, GIA’s laboratories receive an enormous variety of diamonds and colored stones for grading and identification and origin reports. Specimens that are rare or eye-catching or reveal unusual characteristics appear in the quarterly Lab Notes column of Gems & Gemology. Here are G&G’s seven most interesting and unusual from 2019.
1. Diamond on Diamond: CVD Layer Grown on Natural Diamond
A 0.64 ct Fancy grayish greenish blue cushion modified brilliant showed two distinct fluorescence patterns, as well as characteristics of both type Ia and type IIb diamond. The specimen was found to be a composite of a CVD synthetic diamond layer on top of a natural diamond. This was only the second such composite seen at GIA, but it could represent a new type of product entering the market.

Dislocation bundles in the CVD layer are visible under crossed polarizers in methylene iodide. Photo by Troy Ardon; field of view 1.90 mm.
2. Big Sky, Big Ruby: Large Montana Ruby
Montana’s secondary deposits produce sapphire in a wide range of mostly pastel colors. Pink sapphires from Montana are rare, and corundum with enough depth of color to be called ruby are rarer still. A 1.70 ct purplish red octagonal modified brilliant was examined. Its color and large size made it an exceptional specimen—only the second report for a Montana ruby issued by the lab to date.

Inclusions in the 1.70 ct ruby from Montana. Left: Close-up of a glassy melt inclusion with an associated thin film showing geometric patterns; field of view 1.76 mm. Right: A melt inclusion with an iridescent thin film, partial hexagonal zone of particles, and short needles; field of view 3.81 mm. Photomicrographs by Claire Malaquias
3. V for Vanadium: High-Vanadium Color-Change Burmese Sapphire
A 5.68 ct transparent cushion mixed-cut sapphire displayed a strong color change from grayish violet in fluorescent light to purple-pink in incandescent light. Chemical analysis showed an unusually high level of vanadium, the first time the Carlsbad lab had encountered a color-change sapphire with this chemistry profile.

This 5.68 ct cushion mixed-cut sapphire showed a strong color change from grayish violet in fluorescent light to purple-pink in incandescent light. Photo by Robison McMurtry.
4. Neon Faux: Paraíba-Like Synthetic Sapphire
Two gemstones, 7.78 and 4.90 ct, had a neon green-blue to blue-green color similar to that of Paraíba tourmaline. Curved color banding and Plato lines identified them as flame-fusion synthetic sapphire. This was the first time GIA’s Carlsbad lab had examined flame-fusion synthetic sapphire with a Paraíba-like color.

This 7.78 ct round brilliant and 4.90 ct cushion brilliant displayed a blue-green and green-blue color, respectively, that are reminiscent of Paraíba tourmaline. Photograph by Nathan Renfro
5. Not Easy Going Green: Rough Diamond with Fake Green Coating
Natural green diamonds are extremely rare. Their color is typically caused by exposure to radioactive minerals and fluids, which is accompanied by green or brown patches called “radiation stains.” A 6.49 ct green crystal was found to have been coated with chromium oxide powder, followed by annealing of the powder to produce surface plates resembling radiation stains. While the coating was easily detected with magnification, this was a significant attempt to mimic the features of natural green diamonds.

This 6.49 ct rough diamond with patchy green surface color was submitted to GIA’s Carlsbad laboratory for a Colored Diamond Grading Report. Photo by Diego Sanchez
6. Stellar Stellate: Diamond with Remarkable Stellate Cloud
A 3.70 ct faceted Fancy brownish greenish yellow diamond contained an eye-visible stellate cloud inclusion consisting of six legs that each radiated to a point on the polished octahedron. This “asteriated” diamond was striking due to the well-defined nature of the star and the strong yellowish green color it exhibited under long-wave UV. The faceted octahedron cutting style was unconventional, but served to showcase the inclusion scene contained within the diamond.

This 3.70 ct brownish greenish yellow faceted octahedron contained a remarkable stellate hydrogen cloud (left) that showed strong yellowish green fluorescence under long-wave UV light (right). Photos by Diego Sanchez
7. Mega Stars: Large Laboratory-Grown Star Ruby and Sapphire
Two unusually large loose stones with asterism—a 4,759 ct red sphere with a diameter of approximately 76.96 mm, and a 467.2 ct blue cabochon measuring approximately 52.04 × 42.29 × 20.89—were identified as synthetic ruby and synthetic sapphire. While synthetic star corundum is not particularly rare, these were among the largest laboratory-grown star rubies and star sapphires submitted to GIA.

A 4,759 ct synthetic star ruby and a 467.2 ct synthetic star sapphire were submitted to GIA’s Tokyo lab. Photo by Shunsuke Nagai
Be sure to check out every issue of Gems & Gemology for more interesting and unusual Lab Notes. @chapter:27 @chapter:1 @chapter:27


# Publication Year: -
# Title: Bench Tip #15: Modify Your Prong Pushers to Make Them More Versatile
# Abstract: Modify prong pushers

Many stone setters would agree that one of the most challenging aspects of prong setting is getting the prongs down tight on the stone. It’s easy to take this process for granted. If it’s done well, you might never notice. But doing it poorly can result in damaged or lost gemstones, or prongs that snag clothing and feel rough or sharp to the wearer.

A variety of pliers or other tools can be used to push prongs down onto the stone once the bearings have been prepared. This article will focus on prong pushers, which consist of a piece of brass or steel fitted into a wooden handle.

Most common are the flat prong pusher and the grooved prong pusher. While these tools can be used “as is,” a few modifications will make them more versatile.

 Experienced stone setters will customize the face shapes and textures of their prong pushers.
Experienced stone setters often make their own prong pushers from used gravers, files or other tools. These are good options that allow them to reuse worn-out tools and customize the prong pusher for their particular needs, including creating different sizes so they can easily work on larger or smaller prongs and hard-to-reach areas.

	Use a cylinder burr to make a grooved prong pusher.
Many stone setters will also modify the prong pusher’s basic shape, preferring a rectangular face over a square face, which tends to block the view during the setting process. You can use a table-top bench grinder to make these modifications. Just make sure you dip the tools in water frequently as you are grinding to prevent overheating.

Many jewelers also prefer a textured face on their prong pushers. While this may cause minor tool marks on the prong as it is being tightened, the prong tips are often filed down anyway. The advantage of the textured surface is that it keeps the tool from slipping and possibly chipping the stone.

There are many ways to achieve this textured surface, but one is to simply sand across the face of the tool with a relatively coarse (220 or 320 grit) sandpaper.

The modification helps you feel the tool drop into place on the prong, allowing faster and more accurate work.
Another useful modification is to put a groove in the face of the prong pusher to keep it from slipping while you push down the prong. This modification is easily made with a small cylinder bur. By extending the groove across only three-quarters of the face of the tool, you can also put a “stop” in the groove. This is a great trick for working with smaller prongs because it helps you feel the tool drop into place on the prong, allowing faster and more accurate work. @chapter:33 @chapter:2 @chapter:33


# Publication Year: 2018
# Title: Merelaniite Inclusions in Tanzanite
# Abstract: Figure 1. Merelaniite whisker inclusions in the tanzanite cabochon. Photomicrograph by Augusto Castillo; field of view 3.57 mm.

Tanzanite, the blue to violet transparent variety of the mineral zoisite, was discovered in Tanzania around 1967. Since tanzanite seldom contains significant inclusions, the authors were surprised to examine a tanzanite cabochon that contained myriad dense whisker-like inclusions. The whiskers were cylindrical in shape, typically gently curved along their length, and displayed a metallic luster. At first glance, the whiskers were interpreted to be composed of graphite, as it is one of the more common opaque black mineral inclusions found in tanzanite. However, the elongate, curvilinear morphology suggested they were likely something else.
Merelaniite, a new molybdenum-essential member of the cylindrite group, was recently identified by coauthor JAJ and colleagues and approved in 2016 by the Commission of New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association (IMA). The new mineral is sporadically found in specimens from the tanzanite mines near Merelani, Tanzania. It can be associated with a wide variety of minerals from the Merelani mines and has also been noted as being enclosed in calcite, quartz, chabazite, fluorapatite, prehnite, and zoisite. All the specimens identified so far have been obtained from secondary mineral markets, and the exact geological location of any specimen known to contain merelaniite is so far undocumented and unknown. Merelaniite occurs individually and in clusters as dark gray metallic whiskers of circular cross-section. The whiskers are composed of crystal lamellae that are tightly rolled in a “scroll-like” manner similar in appearance to the related mineral cylindrite (J.A. Jaszczak et al., “Merelaniite, Mo4Pb4VSbS15, a new molybdenum-essential member of the cylindrite group, from the Merelani tanzanite deposit, Lelatema Mountains, Manyara region, Tanzania,” Minerals, 2016, Vol. 6, No. 4, 115).
This tanzanite cabochon sample revealed similar whisker-like inclusions accompanied by growth blockages, dark platy crystals, and fractures. The whiskers varied in diameter and length, and tended to branch out intermittently. The length was generally over a millimeter (figure 1). Growth blockages were fluid filled and also contained dark solids (figure 2). The presence of intact liquid inclusions was a strong indicator that this tanzanite had not undergone heat treatment. Small granular crystals were observed in between fractures associated with the whisker inclusions. Raman spectroscopy confirmed these opaque whisker-like inclusions to be merelaniite, and platelets that were associated with the whiskers might be unwound layers of merelaniite.

Figure 2. A growth blockage results from the suspension of zoisite growth when the crystal is interrupted by a foreign body. In this case, the foreign body is a merelaniite whisker. Photomicrograph by Tyler Smith; field of view 1.99 mm.
Coincidentally, two unusual specimens of tanzanite crystals containing merelaniite whiskers were found by one of the coauthors (JAJ) among a gem and mineral dealer’s stock at one of the mineral shows held in Tucson, Arizona, in February 2018. Also relatively unusual is that these crystals were still on matrix composed primarily of calcite and graphite (figure 3).

Figure 3. A merelaniite-included tanzanite crystal (2.2 cm tall, left) on a matrix of calcite and graphite. The calcite also contains merelaniite inclusions. The close-up field of view (right) is 6.55 mm wide. Photos by J.A. Jaszczak.
The occurrence of merelaniite in tanzanite is very rare. This is the first time GIA has identified this new mineral in gem-quality tanzanite. @chapter:12 @chapter:0 @chapter:12


# Publication Year: -
# Title: Discover Mozambique’s Montepuez Ruby Mine with GIA’s Field Gemologists
# Abstract: A Visit to the Montepuez Ruby Mine

	Get an inside view of the world’s most productive ruby mine with GIA field gemologists.

	In this video, you’ll explore Mozambique’s Montepuez ruby deposit with GIA’s dedicated field gemology team. First, you’ll see how the legal owner of the mining rights—Montepuez Ruby Mining (MRM), a subsidiary of the Gemfields corporation—works the area in steps from prospecting through separating the rubies from the ore, to sorting and eventual sale at their Singapore rough auction. You’ll also catch a glimpse of a day in the life of the thousands of unlicensed miners—garimpeiros—who conduct unauthorized mining in the MRM-owned area.

	Since spring 2009, this east African country has emerged as the world’s leading ruby source. As Field Gemologist Vincent Pardieu says of the Montepuez ruby deposit: “I have never seen any place where you have this combination of quantity, nice color, and nice clarity.”

	Every gem miner dreams of finding a big stone one day. “The garimpeiros here, most of them are local (meaning Mozambican) people,” explains Pardieu, “but there are also some Tanzanians here who are working with them. And the Tanzanians have a very good knowledge of ruby mining because you have ruby mining in Tanzania for more than 50 years.”

	Asked about risk, one garimpeiro adds: “Accidents used to happen…people die down there…the soil collapsed and then people die down there.”

	You’ll see the conditions garimpeiros work under—the pits, the dirt—the rubies they find and how they live, and visit a garimpeiro village. “I feel I’m very welcome here!” says geologist Dr. Hsu, with a smile.

	Finally, you’ll visit foreign buyers in Montepuez, which, Pardieu explains, consist of “about 500 to 600 Thai people and about 100 people from Sri Lanka.” The cash gained by these buyers provides the economic impetus for continuing unauthorized mining inside the MRM perimeter.

	This GIA Field Expedition (FE56) took place in September 2014. Besides Pardieu, the participants were cameraman Didier Gruel, Field Gemologist Andy Lucas, Gems & Gemology Technical Editor Dr. Tao Hsu, and Field Gemologist trainee Stanislas Detroyat. @chapter:23 @chapter:2 @chapter:23


# Publication Year: 1991
# Title: Winter 1991 G&G Lab Notes
# Abstract: A Large Chlorite Carving
Treated-Color Diamond with Natural Radiation Stains
Massive Grossularite Garnet Carving
Heat-Damaged Jadeite
Banded Lapis Lazuli
Unusually Large Worked and Plugged Cultured Pearl
Quartzite and Dolomite Bead
Coated Sapphire
Twinned Synthetic Sapphires

To view the full section, download the PDF above. @chapter:43 @chapter:1 @chapter:43


# Publication Year: -
# Title: Alums Named 2013 JCK Rising Stars
# Abstract: GIA alums, from left, Jason Dow, Patrick and Mary Kay Mohs, and Cornelia Goldsmith, are JCK’s 2013 Rising Stars. Photos provided by Jason Dow, Patrick Mohs Jewelry and Cornelia Goldsmith.

                      Four GIA alums have been named “Rising Stars” for the 2013 JCK Las Vegas Show. Each will exhibit their work in the JCK Design Center at the Mandalay Bay Resort & Casino May 31 through June 3. The JCK Rising Star program identifies emerging artists and highlights their designs to buyers at the show.

“We’re so excited and proud that four of our graduates have been selected as this year’s JCK Rising Stars,” said Bev Hori, vice president of Education and chief learning officer for GIA. "This is a great opportunity for them to showcase their design aesthetics and craftsmanship to some of the industry’s most influential buyers.”

Jason Dow channels his heritage in jewelry designs that integrate ancient Asian motifs with modern and Western concepts.
Read More

Cornelia Goldsmith’s designs reflect her enduring love of natural, organic forms that blend ancient and new world sentiments.
Read More

Mary Kay and Patrick Mohs of Patrick Mohs Jewelry find inspiration for their designs in nature.
Read More @chapter:20 @chapter:2 @chapter:20


# Publication Year: 2016
# Title: Book Review: The Eduard Josef Gübelin Story: The Art and Science of Gems
# Abstract: By The Gübelin Group, 233 pp., hardcover, illus., 2014, Unicorn Press, London, $US60.00.

	The Swiss gemologist Dr. Edward J. Gübelin (1913–2005) will be forever linked to the study of inclusions in gems. His work revolutionized gemology: As a result of his groundbreaking research and photomicrography, these internal features are now recognized for their diagnostic value, as indicators of a gem’s identity, geographic source, treated or untreated condition, and natural or synthetic origin.

	This book, written by several family members, chronicles Edward Gübelin’s 65 years of pioneering research but also provides insight into his profound humanity. Even though the work of a research gemologist is often solitary, Dr. Gübelin touched thousands of lives through his prolific writings and photomicrographs, his extensive travels, the work of his laboratory, the educational organizations he helped establish, and the important gem collection he assembled.

	Dr. Gübelin’s impact on my own career began in 1979. I was 22 years old and thrilled to receive a long letter from him complimenting me on my first published article in Gems & Gemology. He encouraged me to continue writing and taking photomicrographs. His letter was articulate and gracious. Indeed, Dr. Gübelin elevated the art of letter writing to a new level of intelligence and eloquence. This letter started a 25-year correspondence and an enduring friendship that extended beyond gemology. He offered kindness, companionship, and advice on many topics. During my travels for GIA, Lucerne always seemed to be on the way to or on the way home from almost any destination. Even my vacations seemed to find me visiting Dr. and Mrs. Gübelin for a few days at their beautiful house on the shores of Lake Lucerne. It was an extraordinary privilege for me, and Dr. Gübelin also inspired and mentored countless other gemologists around the world.

	This richly illustrated volume is much more than an in-depth biography of one of gemology’s most important forefathers. It also provides a glimpse into the development of gemology from its infancy through the end of the 20th century and into the 21st.

	The chapters “Origins, Provenance,” and “Lucerne, Roots” trace the history of the company and family. The second chapter begins, “Eduard Joseph’s private life was all ebb and flow, a continual back and forth to life’s steady rhythms. For him, reconciling his responsibilities as son and heir to the established firm of Gübelin with his passion for science and his duties as a family man was no simple task.” As evidenced by the volume of published work after his retirement from the firm in 1977 until his passing on March 25, 2005, his was truly a life dedicated to gemology. “In fact,” the book notes, “only a few days before he died, he was still studying gemmological problems and exchanging views with his colleagues.”

	Subsequent chapters take the reader along on Dr. Gübelin’s journey from student of mineralogy and gemology in the 1930s to leading expert, and ultimately to the 21st century development of the one of the world’s leading gem laboratories, specializing in geographic origin determination. Dr. Gübelin was a world-class collector of gemstones, an intrepid traveler, teacher, and writer.

	The chapter on his literary contributions begins, “Eduard Joseph recorded his knowledge and experiences in numerous articles, books and contributions. What made them so special is that his vivid and descriptive language was unusual for scientific publications, and yet it made the contents all the more accessible—not just for the expert, but for the lay person too.”

	The book concludes with a synopsis of Dr. Gübelin’s enormous contributions to the gemological and scientific literature, a detailed timeline of milestones, recognitions and awards, and a bibliography of published books and articles.

	This book was preceded by a special limited edition—published in 2013, to commemorate his 100th birthday anniversary—titled Enduring Values: In Celebration of Eduard Josef Gübelin. Few copies of the 2013 special edition were printed; they were distributed as gifts to the clients of the Gübelin Gem Lab and the Gübelin Group. The main difference between the two is that the 2013 edition contained more than 18 personal tributes to Dr. Gübelin from colleagues and family, while the 2014 book contains only three. The remainder of the 2014 book is largely the same, with some differences in graphic layout, paper type, photographs, and text editing.

	This book is a must for any gemologist who is keenly interested in gemstone inclusions. It is especially geared to those seeking to understand the historical origins of gemology, as well as the life and innumerable contributions of one of gemology’s greatest pioneers. @chapter:35 @chapter:1 @chapter:35


# Publication Year: 2018
# Title: Large HPHT-Treated Blue Type IIb Diamond
# Abstract: Figure 1. This 17.09 ct HPHT-treated blue diamond (left) has ragged-looking graphitization around an inclusion (center, field of view 0.76 mm) and high-order interference colors when viewed with crossed polarizing filters (right, field of view 7.19 mm). Photos by Jian Xin (Jae) Liao (left) and Evan Smith (center and right).
Over the past two decades, high-pressure, high-temperature (HPHT) treatment has emerged as a prominent technology for changing the color of diamonds. It is best known for removing brown coloration from natural type IIa material to yield colorless or, rarely, pink diamonds. Similarly, HPHT treatment can be used to reduce the brown color component of gray or brownish natural type IIb (boron-bearing) diamonds, thereby increasing the underlying blue color. Improvements to equipment and methods continue to push the capabilities of HPHT processing.
GIA’s New York lab recently encountered a notably large HPHT-treated Fancy Intense blue oval-cut diamond (figure 1, left). At 17.09 ct, this is the largest HPHT-treated blue diamond graded by GIA to date. For comparison, the average size of most submitted HPHT-processed blue diamonds lies in the 1 to 5 ct range. HPHT treatment can be challenging to detect with standard gemological tools, but in this case the ragged-looking graphitization around an inclusion and the appearance of moderate to high-order interference colors under crossed polarizers were helpful clues (figure 1, center and right). Advanced testing methods (e.g., infrared spectroscopy and photoluminescence spectroscopy) confirmed that the stone was HPHT treated.

Figure 2. Color zonation (left) becomes more noticeable when viewed through the pavilion. The stronger blue-colored region corresponds with bright greenish blue fluorescence in the DiamondView (right, field of view 5.8 mm). Note that the DiamondView image is taken from the opposite side of the diamond. Images by Evan Smith.
Additionally, this diamond had a striking blue color zonation (figure 2, left) that is thought to be unrelated to HPHT treatment. A region of strong blue color is separated from an almost colorless region by a sharp division with octahedral plane {111} orientation. Color zonation is not uncommon in natural type IIb diamonds, though it is seldom so sharp and planar (J.M. King et al., “Characterizing natural-color type IIb blue diamonds,” Winter 1998 G&G, pp. 246–268). The stronger blue region likely contains more uncompensated boron. It also exhibits more intense greenish blue fluorescence/phosphorescence in DiamondView images (figure 2, right). The color boundary might reflect a change in defect incorporation during diamond growth. @chapter:9 @chapter:1 @chapter:9


# Publication Year: 2013
# Title: 21st-Century Jewellery Designers
# Abstract: By Juliet Weir-de La Rochefoucauld, 359 pp., illus., Antique Collectors Club, Woodbridge, UK, 2013. US$95.00

              In this volume, Juliet Weir-de La Rochefoucauld presents highlights from a selection of international contemporary jewelry designers. This hefty opus represents a sort of sequel to the publisher’s Celebrating Jewellery (Bennett and Mascetti, 2012), this time with an eye toward the future of jewelry.

This remarkably illustrated coffee table book prominently displays more than 540 jewelry pieces from 25 of today’s important designers. After a short chapter featuring some of the finest works of the French artist JAR, the author takes the reader on an inspired journey. Twenty sections display the iconic pieces of Kaoru Kay Akihara, Walid Akkad, Lorenz Baumer, Bhagat, Sevan Bicakci, Luz Camino, Wallace Chan, Edmond Chin, Lydia Courteille, Michele Della Valle, Patrice Fabre, James de Givenchy, Vicente Gracia, Hemmerle, Anna Hu, Michelle Ong, Susanne Syz, Nicholas Varney, Stephen Webster, Dickson Yewn, as well as the work of “newcomers” Rami Abboud, Tomasz Donocik, LaMouche, and 10 Royale. The cultural diversity of this ensemble is truly remarkable.

Each section contains a brief background for each designer, along with their diverse creative sources of inspiration, including a list of their favorite themes and motifs. Numerous detailed photos illustrate beautifully how these themes translate into jewelry. Pieces of exceptional craftsmanship are displayed using front-and-back photos. Weir-de La Rochefoucauld gives significant insights into their creative processes and details technical aspects of their jewelry making. Some of the most valuable comments pertain to the innovative materials and techniques used by the designers, including titanium, ceramic, cement, laser welding, and CAD/CAM. The artists also discuss their favorite gemstones and cuts. The book sheds a stimulating light on the use of alternative materials such as wood, leather, ivory mammoth, animal teeth, or old cameos; the choice of bold color and material contrasts to create striking pieces.

In spite of their different sources, the photo renderings are consistent throughout the book. Some of the photos are so sharp that the reader gains a sense of the heft and smoothness of the piece. Gemstone inclusions, special carvings, and jewelry techniques such as micro mosaic, enameling, and special settings, are artfully depicted.

One of this book’s strongest assets is to place the designers and their creations in their artistic and cultural context. Two sections, those on Sevan Bicakci and Wallace Chan, are particularly captivating from both a technical and aesthetic standpoint. The former highlights a rare level of craftsmanship in enameling and stone cutting and the creation of unique rings that celebrate the rich cultural heritage of Bicakci’s native Istanbul. In the latter section, Chan, nicknamed the “Zen Philosopher,” has mastered the use of titanium; he has also invented a way to carve jadeite into a four-prong setting in order to set a precious stone into this matrix. Many of his jewelry pieces refer to some aspects and practices of Buddhism, creating an effect reminiscent of classic Chinese art.

From an aesthetic standpoint, Lydia Courteille and Nicholas Varney stand out for their use of gemstone materials to create unique combinations. Courteille has embraced classic cameos and figurative gem carvings in creating whimsical multicolor cocktail rings, while Varney has mastered the art of incorporating irregular pearls of all shapes into asymmetrical oversized pieces.

One might regret that the selection criteria of these designers are never explained. Were they chosen by generation, prominence, awards won, technical innovation, or auction appeal? One could also fault the unimaginative alphabetical order of presenting them. A thematic arrangement could have provided some interesting comparisons and meaningful conclusions. The alphabetical arrangement also gives way to the repetition of clichés, such as the search for perfection, the need for control over jewelry making, and how each artist is unmistakably guided by their love of the material.

Also, gemologists will note the mention of the species versubianite, presumably a typo for vesuvianite. New Yorkers will quickly catch that LaGuardia Airport is, according to this book, located in New Jersey.

A more basic criticism is that almost no reference is made to actual jewelry size. Since the jewelry designers themselves provided the documentation for this book, these details were probably available. Similarly, no mention is made of photo magnifications, which differ from one page to the next.

With that noted, this luxurious book provides a great source of inspiration for all jewelry scholars, collectors, and professionals at large for envisioning the future trends of the industry. The quality of the photos is an exceptional asset to that end. @chapter:20 @chapter:2 @chapter:20


# Publication Year: -
# Title: Insights From Inclusions
# Abstract: View Gallery

	Natural gemstones are typically far more valuable than synthetics, so being able to identify them correctly is a powerful skill. One of the best ways to determine if a gemstone is natural or synthetic is to note the type and variety of its inclusions.

	Certain types of inclusions are found more often in natural gemstones than in their synthetic counterparts. Needles, clouds, fluids, and crystals are examples of inclusions typically found in natural gemstones.

	Intersecting rutile needles (called “silk”) are inclusions commonly found in corundum. Photo by John I. Koivula/GIA

	A common inclusion observed in amethyst is deep red needles of hematite (magnified 10×). Hematite needles are thin, elongated inclusions. They appear only in natural gemstones. Photo by John I. Koivula/GIA

	Synthetic gems generally have inclusions specific to their method of growth. These characteristics include translucent to opaque coloring, coarseness, and a web-like appearance, which are stark contrasts to natural, transparent, partially healed fracture “fingerprint” inclusions. For example, translucent to opaque-white to yellowish granular-looking flux are types of inclusions you would typically find in a flux-grown synthetic stone.

	Hallmark inclusions of a flux-grown Kashan synthetic ruby are translucent to opaque-white primary flux. Photo by Nathan Renfro/GIA

	“By understanding the types of inclusions and their characteristics, you can determine if a gem is natural or synthetic. That helps you understand the stone’s history and value,” says Brenda Harwick, GIA’s manager of on-campus and laboratory gemology instruction in Carlsbad.

	The three-volume Photoatlas of Inclusions in Gemstones, authored by Eduard Josef Gübelin and John Koivula, is widely considered a definitive read on the subject. To learn more about these valuable resources visit store.gia.edu and enter keyword “Koivula.”

	Some GIA students become so curious about the particular types of minerals that make up inclusions that they pay less attention to the general type of inclusion they are examining.

Here’s a helpful study tip: First become adept at identifying the overall types of inclusions, and then pursue your natural curiosity as to their specific make-up. Advanced chemical and structural testing is often required to determine what they are, but rutile and zircon are some common culprits (depending on the species of gemstones).

	Remember, though, it’s the type and number of inclusions that really matter – and not their precise chemical composition. Keep this in mind, and you will become a better gemologist.

	This Montana sapphire contains dark rutile crystals. When the stone is heat-treated, the titanium dissolves into the host sapphire combining with iron to enhance the blue color of the stone. This internal diffusion of blue color is proof of heat treatment in sapphire. Photo by John I. Koivula/GIA

	This is hydrothermal growth in a synthetic aquamarine. This chevron type of growth structure is indicative of the synthetic origin of this aquamarine. Photo by Nathan Renfro/GIA

	Tips for Viewing Inclusions

	By looking at gemstones under a microscope, you’ll see the number and general type of inclusions. Doing this can help you determine if a gem is natural or synthetic; and that information can affect a gemstone’s value.

	Studying gems under a microscope also helps you create your own “visual library” of inclusions, which over time, will become references as you examine new stones.

	Here are a few tips for using a microscope for this purpose.

		Use a variety of lighting environments to examine inclusions, including: brightfield, darkfield, polarized light, and fiber optic illumination. This lets you see how the gemstone reacts to a controlled pathway of light, revealing valuable information about the inclusions. Each type of light may yield new information and help you see something you would otherwise miss if you only used one lighting environment.

		First look through the broadest window into the gem, which is generally the table facet, and then into the gemstone’s pavilion (this often gives you an excellent view of the inclusions).

		Be certain to rock and tilt the gemstone so that you view it from a variety of angles. @chapter:13 @chapter:0 @chapter:13


# Publication Year: 2000
# Title: Fall 2000 Gem News International
# Abstract: Diamonds
            Apec 2000 International Jewellery Conference Features Diamonds, Education,
            and Treatments
            DeBeers’s Newly Stated Direction
Colored Stones and Organic Materials
            Mosaic Ammonite
            Gemmy Anhydrite from Iran
            Aquamarine from Southeast India
            Coral Exploration Resumes in Hawaii
            Fresnoite: A First Examination
            Gemological Presentations at the 31st International Geological Congress
            Visit to a Malagasy Lapidary Facility
            Rubies (and Sapphires) from Colombia
            Lavender Sugilite with Green Spots
            Paraíba Tourmaline Update
            Tourmaline with an Apparent Change-of-Color in One Pleochroic Direction
Synthetics and Simulants
            Magnetic Hematite Imitation in Jewelry
            Curved Quadruplet Boulder Opal Imitations
Miscellaneous
            Concave Faceting Technique Developed for Sapphires
Announcements
            Visit Gems & Gemology Staff in Tucson
            GANA exhibit at the Carnegie Museum
            GAGTL Conference 2000
            1st Brazilian Symposium on the Treatment and Characterization of Gems
            Fabergé Exhibit in Tucson
            Hong Kong International Jewellery Show
            Diamond Exposition in Paris
            Opal Symposium 2001
            ICA Congress
            Geochemistry and Mineralogy of Gemstones Symposium.

To view the full section, download the PDF above. @chapter:27 @chapter:0 @chapter:27


# Publication Year: 2023
# Title: Exceptional Gemstone Acquisitions by the Kreis Family
# Abstract: Figure 1. A 155 g aquamarine crystal containing a liquid and gas bubble inclusion. The crystal measures 11.9 cm long and the inclusion 4.3 cm long. Photo by Robert Weldon; courtesy of Kreis Jewellery GmbH.
Kreis Jewellery (Niederwörresbach, Germany) is known for master cutting expertise and distinctive jewelry design (see Spring 2022 GNI, pp. 86–87). At the GJX show, Stefan and Alexander Kreis showed us three recent gemstone acquisitions.

	Two-Phase Inclusion in Aquamarine Crystal

First was a 155 g aquamarine crystal containing a two-phase liquid and gas inclusion measuring 4.3 cm long (figure 1; see video). The crystal was found in the 1960s in Marambaia, Minas Gerais, Brazil, and had been part of a private collection before the Kreises obtained it in 2022.
“It would even be a cuttable crystal,” Alexander said. “Of course we would never touch it because of the specialty of the huge liquid inclusion. A liquid chamber that size in quartz would already be amazing,” he continued. “But having it in an aquamarine, which is totally intact—you have the complete termination. And look at the sheer size of that crystal.”
Marambaia was known for large quantities of aquamarine by 1900 and produced the 110.5 kg (244 lb), 552,500 ct Papamel, discovered in 1910, the largest known gem-quality aquamarine crystal. The crystal that was the basis for the Dom Pedro, the largest cut aquamarine, weighed around 45 kg (100 lb) and was also from Marambaia.

Figure 2. A 35.05 ct Sri Lankan cat’s-eye alexandrite in daylight (left) and incandescent light (right). Photo by Robert Weldon; courtesy of Kreis Jewellery GmbH.
Stefan said they had received a 35.05 ct cat’s-eye alexandrite (figure 2) that morning. He noted the size, exceptionally sharp eye, and superb color change for Sri Lankan alexandrite, which typically has a weaker color change than material from Russia and Brazil. Alexander pointed out that cat’s-eyes are less common in alexandrite than in other chrysoberyl. “A cat’s-eye alexandrite with a strong color change like this one is extraordinary,” he said. “A size of 35 carats is what makes it outstanding.”

Figure 3. A 7.08 ct padparadscha sapphire. Photo by Robert Weldon; courtesy of Kreis Jewellery GmbH.
The Kreises also showed us a 7.08 ct padparadscha sapphire (figure 3). “The color mixture of this stone is a real padparadscha color,” Stefan said. Alexander added that a range of colors fall into the padparadscha category, but “this is the perfect color.”
The cat’s-eye alexandrite and padparadscha sapphire will undoubtedly inspire exquisite jewelry designs from Sonja and Vanessa Kreis. Sonja noted, “It is a very intuitive process in which we try to bring out a gem’s natural beauty in such a way that it blurs the boundaries between jewelry and art.” @chapter:27 @chapter:0 @chapter:27


# Publication Year: 2014
# Title: Using Conventional Equipment to Separate Natural from Synthetic Ametrine
# Abstract: Payette F. “A simple approach to separate natural from synthetic ametrine,” The Australian Gemmologist, Vol. 25, No. 4, 2013, pp. 132–141. Photo courtesy of Francine Payette.

              Ametrine is a bicolored quartz variety that contains both amethyst and citrine zones in the same crystal. The only significant source of natural ametrine is eastern Bolivia’s Anahi mine, where it occurs in veins in a dolomitic limestone. The amethyst-citrine bicoloration results from quartz precipitation at very specific geochemical conditions, temperatures, and growth rates. The color of iron-bearing quartz depends on the valence state of the iron. The citrine color in Bolivian ametrine appears to come from the incorporation of very small aggregates of Fe3+. The amethyst color develops in two steps. First, individual Fe3+ ions replace Si4+ ions in the quartz structure. To develop the amethyst color, the crystal must be exposed to ionizing radiation to oxidize the iron in the 4+ state.

Beginning in 1994, Russian gem-quality synthetic ametrine entered the market. Synthetic ametrine can be identified by employing a combination of techniques, such as visible inspection of twinning and color zoning, EDXRF chemical analysis, and IR spectra. In this article, Payette explains the possibilities for separating natural from synthetic ametrine with conventional gem lab equipment.

Quartz is a uniaxial mineral with two unique refractive indeces along its three crystallographic axes. The unique axis is the optic axis. The amethyst-citrine color boundary in natural ametrine is oriented roughly parallel to the optic axis; in synthetic stones, the boundary is oriented at an oblique angle to the optic axis. The gemologist needs only to find the direction of the optic axis to determine whether an ametrine is natural or synthetic. The optic axis in a uniaxial gemstone can be found with a polariscope that has a conoscope lens and, on occasion, with a refractometer.

The conoscope is a polariscope accessory tool. It is a strongly converging, strain-free glass sphere. When a gemstone is positioned between two crossed polarizers, interference colors that are centered in the specimen will be witnessed with the conoscope when the optic axis is exactly perpendicular to the polarizers.

	Polariscope with a conoscope lens. The optic axis perpendicular to the polarizers.  Illustration courtesy of Francine Payette.
In this study, three types of natural and two types of synthetic ametrine were identified using a polariscope with a conoscope lens. Of the three natural stones, one was cut with its table perpendicular to the optic axis, one with its table parallel to the optic axis, and one with its table randomly oriented relative to the optic axis. One synthetic specimen was cut with its table parallel to the optic axis and the other with its table randomly oriented relative to the optic axis.

When a facet perpendicular to the optic axis of a uniaxial gemstone is measured with the refractometer, two constant readings will be observed while rotating the gem. If the facet measured is cut parallel to the optic axis, then the variable shadow will touch the constant shadow at one position during the rotation of the gem. This information enabled the identification of two of the natural samples and one of the synthetic ametrine samples with the refractometer alone. The direction of the optic axis could not be obtained by refractometer readings for the natural and synthetic ametrine samples cut with their table at random orientation to the optic axis, as those readings were not conclusive.

Separating synthetic ametrine from its natural counterpart using conventional gem lab equipment is possible, provided that the gemologist has a good understanding of the morphology and optical mineralogy of both natural and synthetic material. @chapter:5 @chapter:0 @chapter:5


# Publication Year: 2005
# Title: Winter 2005 G&G Lab Notes
# Abstract: Yellow Cubic Zirconia Imitating Cape Diamonds
Orange Diamond Treated by Multiple Processes
Pink Diamonds with a Temporary Color Change
Unusually Large Novelty Cut Diamond
Small Synthetic Diamonds
Diaspore “Vein” in Sapphire
Unusual Pearl from South America
Unusually Small Natural-Color Black Cultured Pearls
Identification of Turquoise with Diffuse Reflectance Infrared Spectroscopy

To view the full section, download the PDF above. @chapter:43 @chapter:1 @chapter:43


# Publication Year: 1988
# Title: An Update on Color in Gems. Part 2: Colors Involving Multiple Atoms and Color Centers
# Abstract: This is the second part in a three-part series on the origin of color in gem materials. This article discusses colors produced by (1) processes that involve multiple atoms (e.g., blue sapphire, organic products), and (2) a variety of defect structures that are generally created by irradiation (natural or artificial), known collectively as "color centers" (e.g., green diamond). @chapter:18 @chapter:1 @chapter:18


# Publication Year: 2013
# Title: Undisclosed Samples of Large CVD Synthetic Diamond
# Abstract: Figure 1. Six large CVD synthetic diamonds (1.001–1.119 ct) were submitted for grading undisclosed. Photo by H. Kitawaki.

              In mid-2012, one of the international diamond grading laboratories in Antwerp reported undisclosed CVD synthetic diamonds, causing a stir in the diamond industry (C. Even-Zohar, “Synthetics specifically ‘made to defraud,’” Diamond Intelligence Briefs, Vol. 27, No. 709, 2012, pp. 7281–7290). Since then, reports of undisclosed CVD synthetics have also emerged from gem testing laboratories in India and China (Z. Song et al., “The identification features of undisclosed loose and mounted CVD synthetic diamonds which have appeared recently in the NGTC laboratory,” Journal of Gemmology, Vol. 33, No. 1–4, 2012, pp. 45–48). While those samples were mostly between 0.3 and 0.5 ct, the largest colorless CVD synthetic reported by a gem laboratory so far was a 1.05 ct pear shape submitted to GIA (Summer 2010 G&G Lab Notes, pp. 143–144).

In December 2012, six CVD synthetics over one carat (figure 1) were submitted to the Tokyo branch of the Central Gem Laboratory for diamond grading. These were among the largest undisclosed samples of CVD synthetic diamond ever submitted to a gem laboratory. The six round brilliants ranged from 1.001 to 1.119 ct. All had a color grade of Light yellowish gray, and their strong grayish hue made color estimation using “Cape” series master stones difficult. Four of the samples had a clarity grade of VS1, while the other two were VS2. Four samples had cut grades of Excellent, and two were Very Good.

Each sample contained a few pinpoint inclusions, which kept the clarity grades below VVS. The dark, irregularly shaped inclusions were presumably non-diamond carbon. Some samples showed dark graphitization on the girdle. A similar feature is seen in HPHT-treated diamond, which strongly suggests that these samples underwent post-growth treatment. The characteristic streak pattern of anomalous double refraction due to strain (low-order black and white interference colors) was observed in every sample. The streaks run parallel with the growth direction of the crystal, which is perpendicular to the seed face. The patterns were elongated along the crystal’s growth direction and presumably caused by dislocation during growth (figure 2). The samples were inert to long-wave UV radiation, while some of them displayed weak greenish yellow luminescence to short-wave UV.

	Figure 2. Anomalous double refraction due to stress was observed under cross-polarized filters. Contrasting black and white low-order interference colors produced the streak pattern. Photo by H. Kitawaki.
After FTIR analysis, the samples were classified as type II, which do not show any distinct absorption in the nitrogen area (1500–1000 cm–1) in diamond. Despite their yellow tint, the 1344 cm–1 absorption attributed to single substitutional nitrogen was not observed. Absorptions also originate in hydrogen at 3123 cm–1, which has been reported as a characteristic of CVD-grown diamond (W. Wang et al., “Gem-quality synthetic diamonds grown by the chemical vapor deposition method,” Summer 2012 G&G, pp. 268–283), and at 3107 cm–1, which is often seen in natural diamonds, were not recognized as clear peaks.

Photoluminescence analysis at liquid-nitrogen temperatures with various excitation wavelengths revealed peaks at 637 nm (NV–), 575 nm (NV0), 503.2 nm (H3), and 737 nm (SiV–; 736.4/736.8 doublet). With 488 nm laser excitation, five of the six samples displayed a 528 nm peak of unknown origin. With 325 nm excitation, 462 and 499 nm peaks with unknown origins were detected. These two peaks are not observed in natural diamonds. Two of the samples showed a very weak peak at 415.2 nm (N3).

When tested with the DiamondView, the samples showed blue phosphorescence and greenish blue-white luminescence. This luminescence is attributed to boron doping, an enhancement that makes the stone colorless (D.S. Misra, “Method for growing white color diamonds by using diborane and nitrogen in combination in a microwave plasma chemical vapor deposition system,” International Patent No. 2012044251).

The samples also showed the layered structure image characteristic of CVD synthetic diamond (figure 3). These UV luminescence figures, unique to CVD synthetics, are more apparent from the pavilion than from the table. Some of them displayed straight growth lines or linear structures such as slip lines, and careful observation of the entire stone (especially from the pavilion) is imperative.

	Figure 3. DiamondView fluorescence images showed a layered structure characteristic of CVD synthetic diamond. Blue phosphorescence, attributed to boron, was also observed. Photo by M. Hisanaga. @chapter:36 @chapter:1 @chapter:36


# Publication Year: -
# Title: Romancing the Source: Myanmar
# Abstract: Myanmar

	Mogok, Myanmar, is perhaps the world’s most exotic and romantic gem-producing area.

	This series of articles and videos follows a team of GIA Field Gemologists on their travels from the mountains of Afghanistan to the jungles of Sri Lanka in search of the sources of colored gemstones and the people who pursue them. This thrilling journey will take you to remote gemstone-mining areas, where you’ll witness the extreme effort required to wrestle nature’s treasures from the earth.

Mogok, Myanmar, also known as The Valley of Rubies, is perhaps one of the world’s most exotic locations. Photo by Andrew Lucas/GIA.

	The romance of a colored gemstone arises from its beauty, the exotic qualities of its source’s location, the adventure leading to its discovery, and the stories of the people who seek it. These factors have united to create the allure of gemstones through the ages, and continue to do so even in modern times.

	Mogok, Myanmar, has become as famous as the magnificent rubies, sapphires, spinels, and other gems it produces. It is an amazing area, dotted with pagodas, temples, Buddha statues, and outcroppings of marble rock.

	The people are as exotic as the location, blending populations of Burmese, Shan, Lissu, Karen, and former British Nepalese troops called Ghurkas. Most exotic of all are the Kanase women. By tradition, these women have the right to mine the tailings of mining operations in search of gemstones, surrounded by what often appears to be a sea of white marble. They wear traditional painted or cone-shaped hats and decorate their faces with a white paste.

	Mogok miners engage in all types of colored gemstone mining, and the local gem markets are as colorful as the miners. @chapter:40 @chapter:2 @chapter:40


# Publication Year: 2020
# Title: Carvings from Bali
# Abstract: Figure 1. These miniature opal carvings are favored by designers. They are hand-carved in Bali from different varieties of Australian opal. Photos by Tao Hsu and Jennifer Stone-Sundberg.
Picturesque beaches and lush green jungles are not the only attractions that make Bali the most popular tourist destination in Indonesia. The local carving tradition, derived mostly from woodcarving, adds a layer of artistry and craftsmanship to this tropical paradise. Now many carvers there are also involved in different types of gem materials.
At the GJX show, the author found some authentic and attractive Balinese carvings of Australian opal, mammoth tusk, and bovine bone. Mr. Terry Coldham from Intogems brought opal carvings of pendant sizes, which are highly desired by jewelry designers (figure 1). Mr. Coldham utilizes rough from different Australian mining areas, primarily black and white opal, but some crystal opal as well. The carvings feature natural themes such as plants, flowers, and animals, as well as profiles of faces from different cultures. The carving style includes both relief panel and three-dimensional sculpture. Some pieces show color blocks being skillfully arranged, a technique commonly used by the Chinese in jade carving. The quality of the rough dictates the price, ranging from hundreds to thousands of dollars for each finished piece. According to Mr. Coldham, opal carvings have sold well over the past several years. He enjoys working with the Balinese carvers and added that after a couple of years of collaboration, the products have improved to better fit the international market.

Figure 2. Balinese carved mammoth tusk of a garden goddess. Photo by Tao Hsu.

Figure 3. Bovine bone carvings are usually dyed to show vivid colors. The color is stable over many years. Photo by Tao Hsu.
Another exhibitor that caught the author’s eye is Susan Tereba. Ms. Tereba moved to Bali over 30 years ago and still lives there today. She brought to the show amazing hand-carved mammoth tusk and bovine bone. Ms. Tereba appreciates the remarkable talent of the Balinese carvers, who are fast learners and can easily grasp themes that are not indigenous. These exquisite carvings also show a wide variety of motifs, with animals and goddesses the most popular and some pieces are gem studded (figure 2). The bovine bone carvings are dyed, and according to Ms. Tereba the color is very durable and resistant to wear (figure 3). Jewelry designers and hobbyists are her main clients.
Watch videos of Terry Coldham and Susan Tereba displaying Balinese carvings:

	Terry Coldham displaying Balinese opal carvings

	Balinese carvings by Susan Tereba @chapter:55 @chapter:2 @chapter:55


# Publication Year: 2016
# Title: Quarterly Crystal: Quartz and Lazulite
# Abstract: Figure 1. Recovered from Canada’s Yukon Territory, these doubly terminated parallel-growth quartz crystals are decorated with deep blue crystals of lazulite. This specimen weighs 76.19 ct and measures 36.12 × 22.24 × 16.95 mm. Photo by Kevin Schumacher.

	Before a gemstone is fashioned by a lapidary, it enters the gem trade in its natural state, in a form generally referred to as “rough” or “gem rough.” Not all rough is gem quality, nor is most so-called rough appropriate for fine mineral collections. Only a very special piece of rough is suitable for gem use or fits the visual definition of a fine mineral specimen. When such crystals are encountered it then becomes a difficult decision, often financially based, whether to leave them in a natural state or fashion them into polished gems.

	Our new “Quarterly Crystal” section of the Micro-World column will feature very attractive inclusion-bearing minerals that could also be fashioned by a skilled lapidary into a gem or a polished inclusion study block. The quartz and lazulite specimen shown in figure 1 is one such mineral.

	These parallel-growth, doubly terminated glassy quartz crystals were recovered from Rapid Creek in the Dawson mining district of Canada’s Yukon Territory. While this is a nearly perfect mineral specimen, hosting swarms of deep blue lazulite crystals both on the surface and within (figure 2), it also makes a remarkable piece for any inclusionist’s collection. Since this is a very uncommon mineral association from the locality, whether to polish it is a difficult decision. Fortunately, this dilemma can often be avoided with a simple trick: A small drop of mineral oil placed on the surface serves as a temporary window through which the inclusions may be observed and photographed.

Figure 2. Inclusions of lazulite in this Canadian quartz were photographed using a partial immersion technique. A drop of mineral oil was placed on the surface to create a temporary window into the interior. Photomicrograph by Nathan Renfro; field of view 4.45 mm. @chapter:0 @chapter:0 @chapter:0


# Publication Year: 2023
# Title: Spring 2023 Auction Highlights
# Abstract: Figure 1. The Bulgari Laguna Blu, an 11.16 ct Fancy Vivid blue diamond, was featured for the first time at auction in Geneva. Courtesy of Sotheby’s.
Following a lackluster start to the auction season in Hong Kong, all eyes were on the estate of late Austrian billionaire Heidi Horten in May, presented by Christie’s in Geneva. Leading up to the three-part auction, the collection made headlines due to the controversial source of Horten’s wealth. (Horten’s late husband reportedly made his fortune buying businesses from Jews forced to sell well below value in Nazi Germany.) Despite the controversy, the sale became the most lucrative jewelry auction in history, garnering $202.2 million and surpassing the 2011 auction of Elizabeth Taylor’s estate, which totaled $116 million. In accordance with her wishes, proceeds from Horten’s estate were donated to a foundation for medical research, child welfare, and access to the arts, while Christie’s pledged to donate part of its commission to Holocaust-related charities.
Also in Geneva, Sotheby’s rebounded from a disappointing fall 2022 auction season for colored diamonds (Winter 2022 GNI, pp. 524–526) with the sale of the Bulgari Laguna Blu (figure 1). Cut by Bulgari in the 1970s for a private collector, the 11.16 ct Fancy Vivid blue diamond made its auction debut, selling just above its estimate at $25.2 million after only four minutes of bidding. As the highest-priced gem Bulgari has ever sold, the VS1, type IIb diamond also holds GIA’s highest color grade for a blue diamond.

Figure 2. The 126.76 ct Internally Flawless Light of Peace diamond sold for $13.6 million. Courtesy of Christie’s.
The season ended on a high note in June with the New York auctions. Leading Christie’s Magnificent Jewels sale, the 126.76 ct Internally Flawless Light of Peace diamond (figure 2) was offered without a reserve. Selling within its presale estimate, the GIA-graded type IIa diamond garnered $13.6 million. The largest stone cut from a 435 ct rough unearthed in West Africa, the Light of Peace was once owned by the Zale family, who used the diamond to fund peace-supporting missions. To continue this legacy of goodwill, a portion of the proceeds from the auction will be donated to the United Nations High Commissioner for Refugees.

Figure 3. The Estrela de Fura, a 55.22 ct ruby from Mozambique, became the largest and highest-priced ruby ever sold at auction. Courtesy of Sotheby’s.
At Sotheby’s Magnificent Jewels auction, two gems smashed multiple records. The Estrela de Fura (figure 3), a 55.22 ct “pigeon’s blood” ruby, became both the largest and most expensive ruby ever to sell at auction, raking in $34.8 million. The gem was cut from a 101 ct rough mined in Mozambique in July 2022, which made headlines as the largest gem-quality ruby ever discovered. Remarkable not only for its unprecedented size, the Estrela de Fura’s florescence, clarity, and vivid red hue rival that of Burmese rubies. A portion of the proceeds from the sale will help establish the Fura Training Academy in Mozambique, encouraging access for locals to education and technical training in areas such as mining, engineering, carpentry, and agriculture.

Figure 4. The 10.57 ct Eternal Pink diamond set a new record per-carat price at $3.3 million. Courtesy of Sotheby’s.
Also selling for $34.8 million, the Eternal Pink (figure 4), a 10.57 ct Internally Flawless Fancy Vivid purplish pink diamond, fell just short of its estimate but still surpassed the previous record for a diamond of this color grade. The GIA-graded diamond, which was cut from a 23.78 ct rough from Botswana, set a new record price per carat at $3.3 million. Sales of the Eternal Pink and the Estrela de Fura helped Sotheby’s break two more records, becoming the first auction to sell two items for more than $30 million each and achieving the highest total ever for a jewelry auction at Sotheby’s New York. The overall sale brought in $95.9 million, topping the house’s previous record of $65.1 million from April 2015. @chapter:37 @chapter:3 @chapter:37


# Publication Year: 2020
# Title: Nephrite Jade from Multiple Sources
# Abstract: Figure 1. This bead strand is from Pakistan (9 mm beads), while the bead bracelet is from Siberia (20 mm beads). Green nephrite from Pakistan has a very similar appearance to material from British Columbia. The Siberian beads are much brighter. Photo by Kevin Schumacher.
Green nephrite deposits are found at many locations around the globe, with British Columbia, Siberia, and northwestern China as the leading producers. Old and still active subduction zones with ophiolite have the potential to produce green nephrite. This is because green nephrite bodies are closely associated with their serpentinite host rocks, part of the ophiolite exposed on land when an ocean basin closes. All major green nephrite deposits cluster in this type of convergent-margin environment.
At the 2020 GJX show, Nikki Makepeace from Jade West in British Columbia showed the authors nephrite pieces from Pakistan, an emerging green nephrite source. The green to dark green appearance and the quality of these pieces (such as the bead strand in figure 1) are very similar to the production from British Columbia. In comparison, green nephrite from Siberia shows brighter colors (the bracelet in figure 1 and the pendant in figure 2). Ms. Makepeace informed the authors that the production from Pakistan is quite substantial.

Figure 2. High-quality nephrite from Siberia can sometimes show a color similar to that of green jadeite. Photo by Tao Hsu.
The earliest report on Pakistan nephrite was published in 1963, with the positive identification of two pebbles collected in 1955 in the riverbed of the Teri Toi in Kohat District of Pakistan (B.C.M. Butler, “Nephrite jade in West Pakistan,” The Journal of the Royal Asiatic Society of Great Britain and Ireland, No. 3/4, 1963, pp. 130–139). The geographical location of this deposit placed it in the collision belt along the Himalaya Mountains. This is the convergent margin between the Eurasian and Indian Plate when the Tethys Ocean closed about 50 million years ago, providing an ideal geological environment for nephrite formation.
In addition to the goods from Pakistan, the authors saw a large koru, a spiral shape often used in Maori art, made of nephrite from Afghanistan. Currently, Afghani materials are scarce on the international market. The only information the authors could find was that the rough comes from the Kohi-Safi District of central Parwan Province. This location is not far from the Pakistani deposit.
While buyers are still waiting to see more production from these emerging sources, green nephrite from British Columbia and Siberia still dominate the market. Siberian goods in general demand higher prices than materials from the rest of the world due to their brighter colors. British Columbian production is still high and can supply finished goods of all price ranges. @chapter:46 @chapter:0 @chapter:46


# Publication Year: 2014
# Title: An Unusual Doublet Set in Fine Jewelry
# Abstract: Figure 1. This green oval resembling an emerald proved to be a doublet with a beryl top and a topaz bottom. Photo by Olivier Segura.

              The Laboratoire Français de Gemmologie (LFG) examined a finely made white gold ring set with a green oval faceted stone that measured approximately 20.2 × 14.7 × 8.6 mm and resembled an emerald (figure 1). The stone showed distinct parallel growth zones, visible to the eye, under the table and the crown. These slightly undulating features (figure 2) were strongly reminiscent of Russian hydrothermal synthetic emerald (see, e.g., K. Schmetzer, “Growth method and growth-related properties of a new type of Russian hydrothermal synthetic emerald,” Spring 1996 G&G, pp. 40–43).

Figure 2. Slightly undulating growth zones under the table and crown were reminiscent of Russian hydrothermal synthetic emerald. Photomicrograph by Alexandre Droux; magnified 80×.
The pavilion showed fingerprint-like inclusions consisting of droplets that were easily visible with the loupe (figure 3). This feature might lead one to believe it was a flux synthetic emerald, inconsistent with the observations on the crown. Magnification reveals, however, that the fingerprint-like inclusions are actually made up of very small cavities, with bubbles that are clearly visible in the larger cavities. Therefore, the pavilion is actually a natural gem.

Figure 3. Fingerprint-like patterns reminiscent of flux synthetics are in fact very small two-phase liquid-gas inclusions. Photomicrograph by Alexandre Droux; magnified 80×.
At the level of the girdle, close examination revealed one area with a separation line, hidden elsewhere because of the closed setting (figure 4). Through the table, small but prominent black spots occurred on a single plane. These were flat bubbles in cement introduced at the separation plane.

Figure 4. These small black spots are flat bubbles in cement along a separation plane. The line of separation was noticeable through the crown in only one area. Photomicrograph by Alexandre Droux; magnified 30×.
Only the crown appeared a weak red under the Chelsea filter. Under short-wave ultraviolet radiation, the upper part was inert while the lower part showed a light blue, milky luminescence. Under long-wave UV, both were inert. Therefore, the green oval was clearly a doublet (R. Webster, Gems: Their Sources, Descriptions and Identification, 4th ed., rev. by B.W. Anderson, Butterworths, London, pp. 457–468). The refractive index was impossible to measure on either the table or the pavilion because the prongs extended into these two areas.

Raman spectroscopy with a 514 nm laser and 4 cm–1 resolution identified the crown as beryl and the pavilion as topaz. Hence the central stone of the ring is a doublet with a hydrothermal synthetic emerald top and a topaz bottom, which is quite unusual.

This case is consistent with an earlier report (J. Hyršl and U. Henn, “Synthetische smaragd-topas-dublette,” Zeitschrift der Deutschen Gemmologischen Gesellschaft, Vol. 60, No. 3–4, pp. 111–112), which noted that the doublets were of Indian origin. The luminescence of the topaz bottom is slightly different in the present doublet, though still within the known variations of topaz luminescence.

Today far fewer doublets are being submitted to gemological laboratories. This specimen’s unusual setting, closed at the girdle and with large prongs preventing access to the table and pavilion for refractometer measurement, suggests an intent to disguise the composite (and partially synthetic) nature of the central gem. Even fine jewelry can be set with gems that are not natural, and gemologists should remain wary of doublets. @chapter:10 @chapter:0 @chapter:10


# Publication Year: 2020
# 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. @chapter:52 @chapter:1 @chapter:52


# Publication Year: 2023
# Title: HPHT-Grown Colorless Diamond Displaying Unusual Phosphorescence Effects
# Abstract: Figure 1. Top: A series of images showing the gradual change (left to right) in the phosphorescence of the 0.71 ct HPHT-grown colorless diamond after removing it from the LWUV source (left image) in increments of 30 seconds for 150 seconds (right image). Bottom: The gradual change in phosphorescence after exposure to a SWUV source (left image) in increments of 30 seconds. The greenish blue and orange emissions decay differently, with the blue fading faster (~90 seconds, fourth image from left) than the orange (~240 seconds, right image). Images by Guy Borenstein.
Phosphorescence longer than 10 seconds in reaction to ultraviolet radiation is regularly observed in colorless to near-colorless and blue-colored diamonds grown by a high-pressure, high-temperature (HPHT) technique. The gemological laboratory of Stuller Inc. recently tested an HPHT-grown colorless (approximately E color grade with a blue-gray overtone) oval brilliant diamond weighing 0.71 ct that showed unusual fluorescence and phosphorescence reactions.
When exposed to a long-wave ultraviolet (LWUV, 365 nm) source for 60 seconds using a standard UV viewing cabinet, the stone emitted a gradually increasing strong orange fluorescence, followed by a long-lasting noticeable phosphorescence (~150 seconds, figure 1, top). The fluorescence and phosphorescence reactions demonstrated a nonuniform color distribution. Similar results were observed using other light sources, including 395 nm UV LED, 405 nm blue laser, a tungsten incandescent flashlight, and a fiber-optic halogen unit.
Given that orange phosphorescence can also be generated by low- and non-UV light sources, further analysis was performed using a series of spectral bandpass filters to identify other wavelengths that stimulate the orange phosphorescence. Testing demonstrated that medium- to strong-intensity light centered at around 430 nm produces the excitation.
Under short-wave ultraviolet (SWUV, 254 nm) radiation using a standard viewing UV cabinet and a De Beers PhosView instrument, the stone displayed a mix of strong greenish blue and medium orange zoned fluorescence and phosphorescence (figure 1, bottom). The colored phosphorescing areas decayed at different rates, with the greenish blue fading faster than the orange (~90 seconds vs. ~240 seconds, with a half-life of about 25 and 35 seconds, respectively).

Figure 2. Deep-UV imaging of the 0.71 ct colorless diamond showing a cuboctahedral-structured luminescence associated with HPHT growth. Image by Guy Borenstein.
Deep-UV (<225 nm) imaging demonstrated a strong greenish blue fluorescence with a clear cuboctahedral structure associated with HPHT growth (figure 2). After removal from the excitation source, the stone displayed a phosphorescence reaction similar to the reaction under SWUV.

Figure 3. The infrared spectrum of the 0.71 ct HPHT-grown diamond revealed it was type IIb with relatively high levels of uncompensated boron (for a colorless diamond) at 4089, 2929, 2800, and 2455 cm–1.
Infrared spectroscopy revealed a type IIb diamond with relatively high levels of electrically uncompensated boron at 4089, 2929, 2800, and 2455 cm–1 (figure 3). Photoluminescence spectroscopy with 532 nm laser excitation at liquid nitrogen temperature (77K) showed no results, except for the diamond’s first- and second-order Raman spectrum peaks, a common tendency in HPHT-grown colorless diamonds (S. Eaton-Magaña et al., “Observations on HPHT-grown synthetic diamonds: A review,” Fall 2017 G&G, pp. 262–284).
The two phosphorescence colors emitted and their relatively long duration are well-known properties of HPHT-grown diamonds (S. Eaton-Magaña and R. Lu, “Phosphorescence in type IIb diamonds,” Diamond and Related Materials, Vol. 20, No. 7, 2011, pp. 983–989; Eaton-Magaña et al., 2017), and a blue-orange luminescence combination in one gem was also previously reported (Eaton-Magaña and Lu., 2011; B. Deljanin et al., “NDT breaking the 10 carat barrier: World record faceted and gem-quality synthetic diamonds investigated,” Contributions to Gemology, Vol. 15, No. 1, 2015) but of weaker intensity. The laboratory-grown diamond’s property of bicolor, decay-varying phosphorescence has been previously reported as well (K. Watanabe et al., “Phosphorescence in high-pressure synthetic diamond,” Diamond and Related Materials, Vol. 6, No. 1, 1997, pp. 99–106; Eaton-Magaña and Lu, 2011; Ulrika F.S. D’Haenens-Johansson et al., “Large colorless HPHT-grown synthetic gem diamonds from New Diamond Technology, Russia,” Fall 2015 G&G, pp. 260–279).
Considering the HPHT growth method, the long-lasting greenish blue phosphorescence produced by exposure to SWUV and deep UV was expected. It was previously suggested to be related to nitrogen-boron donor-acceptor pair recombination (Watanabe et al., 1997). However, the orange phosphorescence demonstrated a new stimulation source. Its combination with the greenish blue phosphorescence and the identified visible-light excitation wavelength reinforces the theory that the recorded orange phosphorescence is of a different donor-acceptor pairing.
Light of 430 nm wavelength can be found in most fluorescent and all incandescent indoor light sources, as well as the desk lamps and color grading cabinets found in gemological laboratories. Therefore, considering the possibility of more diamonds with this property in the market, their phosphorescence produced from visible light makes it challenging to assign a color in the colorless to near-colorless range for these diamonds during grading. Even under standard non- or low-UV output 6500K fluorescent bulbs, the orange luminescence generated by the source becomes noticeable, adding a yellowish overtone to the blue-gray bodycolor and changing its apparent color grade to approximately F to G. Such a change may impair the diamond grader’s ability to accurately assess the stone’s bodycolor. @chapter:22 @chapter:1 @chapter:22