# Publication Year: -
# Title: 30-Year Marine Corps Veteran Fulfills Dream of Becoming a Field Gemologist
# Abstract: Retired Master Gunnery Sergeant Manuel Diaz, GG, has found that his extensive experience in “jungle environments around the world” prepared him well for the rigors of field gemology. Here, Diaz traverses jungle-covered kharsts while climbing the Cung Truoi spinel mining cliff in Vietnam. Diaz, an independent gemologist, joined GIA's team from Bangkok on a field expedition there in the spring of 2015. Photo by Vincent Pardieu/GIA

Editor's Note: This article was originally published on Nov. 28, 2016 and has been updated.

Whether exploring jungles in Madagascar or riverbeds in San Diego County, Manuel “Manny” Diaz likes to say he’s “living the dream.”

And what a dream it is: after retiring from the United States Marine Corps with more than three decades of service and 20 deployments, Diaz finally pursued his decades-long goal of earning a Graduate Gemologist diploma from GIA and began to work as an independent field gemologist.

For Diaz, the gem and jewelry trade is no mere industry, but a family that embraced and mentored him as an 18-year-old Marine.

“On my first overseas assignment, I was on ‘R&R’ and was introduced to a gem broker who worked with Australian opals,” Diaz says. “He was friendly and open to questions and gave me my first introduction to the ‘mine to market’ concept – then he introduced me to many others along that journey. I was befriended worldwide by brokers, miners, cutters, jewelers − even pearl divers for the Bahrain royal pearl beds.”

Manuel Diaz, third from left in the back row, served 20 deployments over three decades in the United States Marine Corps. Diaz, who earned his GIA Graduate Gemologist diploma immediately after his 2014 retirement from the Marine Corps, is pictured here on his final deployment, to Afghanistan. Courtesy of Manuel Diaz
The more Diaz traveled with the military, the more he met like-minded gem enthusiasts. In 1987, while stationed in the Philippines, he began to research how he could gain a formal education in gems and minerals.

“I came across GIA in a reference book, and promised myself that I would attend any and all courses they offered when I completed my Marine duties,” he says.

As Diaz gained a working knowledge of gems, minerals and the supply chain, his information proved useful for military operations. On one combat deployment, Diaz was required to investigate and advise how Marines might reduce conflict at a nearby marble quarry. Hostile forces there were taking over the deposits, stealing income and trade revenue from the rightful owners.

“Some personnel immediately recommended air and artillery bombardment to the quarry,” Diaz says. “But having an experienced knowledge of mining operations, I quelled those ideas for a more tactical approach. The quarry began operations that soon deterred the hostiles and kept them from taking advantage of the deposits. It reduced the income base for hostile forces and increased revenue for the indigenous people.”

Diaz also found that his fellow Marines wanted to tag along on his exploratory trips during their “R&R” breaks.

“There were times I would take 10-20 people on a trip and teach them about gems and participate in their personal trades,” he says.

Manuel Diaz, addressing the crowd at his 2014 retirement ceremony at the Marine Corps Base Camp Pendleton, says that no one in his family was surprised at his career change. He spent his off-time on international deployments exploring and learning about the local gem and jewelry industry. Courtesy of Manuel Diaz
Diaz was able to pursue his dream in 2014 when he retired as a Master Gunnery Sgt. from the First Marine Expeditionary Force at Marine Corps Base Camp Pendleton – just a 20-minute drive from GIA’s World Headquarters in Carlsbad. He used the G.I. Bill to begin his studies online and on campus immediately and by the end of the year, earned his AJP, Graduate Pearls and Graduate Gemologist diplomas.

As a student, Diaz attended a lecture by former GIA field gemologist Vincent Pardieu, and approached him to talk afterward. Soon after, Diaz was on his first expedition as an independent field gemologist, traveling along with a GIA team to Vietnam. It turned out that Diaz – who had extensive experience in expeditionary engineering, international security, emergency response management and military special operations (including serving the U.S. Department of State as a Security Guard Detachment Commander for consulates and embassies in Athens, Greece and Addis Ababa, Ethiopia) – was well-equipped to handle the rigors and often-harrowing conditions of field expeditions.

“I had 30 years to hone my skills in packing and personal equipment preparation for long durations,” he says. “Nowhere else could a person gain the experience and knowledge given a Marine going through deployment preparation and execution. Our thought process is different – foreign for someone who has not had to survive a life-altering experience.

“It’s not that there are no new experiences for me, but I travel prepared, regardless of location and time on deck,” says Diaz, who is also certified as a master scuba diver. “With the ‘ruby rush’ expedition to Madagascar, for example, I was familiar with the conditions – it wasn’t the first time I visited Madagascar – and I have a huge amount of experience in jungle environments around the world.

“Know yourself and seek self-improvement – no one is going to do it for you,” says field gemologist Manuel Diaz, pictured in a morning gem market at Yên Thế, Lục Yên, Yên Bái, Vietnam. After a three-decade career in the military, Diaz followed a longtime dream to join the gem and jewelry industry. Photo by Vincent Pardieu/GIA
That preparedness − and not being unsettled by harsh terrain, aggressive people or even life-threatening experiences that could rattle those less-experienced – make it possible for Diaz to focus on the people involved.

“As a Marine, you find that it’s all about those people who are with and around you,” he says. “For me, the experience in field gemology is about the people I come in contact with. Finding the gem is key, but finding it with those around you – that’s the reason for me being there.”

The last year has been full and varied for Diaz, from working in Mozambique and conducting market research for a private mining company to teaching junior and senior high school students about the geological development of minerals.

Diaz, who lives in north San Diego County with his family and volunteers as a docent for the Fallbrook Gem and Mineral Society, also enjoys helping individuals hunt for gems close to home.

“If a family wants a particular quartz variety, a collector wants to explore a show or market, or a young couple wants a lesson on gem and jewelry purchases, I’m their guy,” he says. “Nothing is more important than tending to the needs and passions of my clients.”

Diaz says his time at GIA – and the “dedicated” faculty and staff members who became like extended family to him – opened the doors to professional dreams that were decades in the making. He is also trying to help other veterans find what lies ahead for them after the military by encouraging them to consider the gem and jewelry industry.

“I’ve lured a few of them to GIA,” he says. “Using the G.I. Bill for my GIA education was a great resource and a comfort for me – that is priceless.”

Manuel Diaz, here studying a blue spinel in Vietnam, says his GIA training equipped him to communicate with clients. “Being able to describe color in such a clear manner is helpful for not only grading, but in being able to explain it to clients looking for a particular hue or saturation in a gem,” he says. Photo by Lucie Martinez/GIA
One of those veterans is Diaz’s brother, Ramon – also a 30-year veteran of the Marine Corps and a retired Master Gunnery Sergeant. Ramon Diaz graduated in 2015 with a Graduate Jeweler diploma and in 2016 with a Jewelry Design and Technology diploma from the Institute.

The brothers are mulling how they might work together in the future, whether that is in the field or helping people learn about and buy gems. But Diaz knows one thing for sure.

“I’m in this for the find,” he says. “Not money, not fame. Simply the find.” @chapter:23 @chapter:2 @chapter:23


# Publication Year: -
# Title: Don’t Miss Out on 2016 Continuing Education Recognition Program
# Abstract: The 2016 Continuing Education Recognition Program covers Australian sapphires and opals, Montana sapphires, Tennessee mother-of-pearl, and much more.

	Diamonds from Canada’s frozen Northwest Territories. Opals and sapphires from Australia. Traditional jewelry from India.

	These are just some of the gems and jewelry you will learn more about as you travel with GIA field gemologists to the source in this year’s Continuing Education Recognition Program. Created for alumni who hold a GIA Graduate Gemologist or Gemologist diploma, the continuing education program includes a variety of engaging slideshows and animation, interactive self-testing, instructional videos and expert interviews, featuring the most up-to-date discoveries and research. The program is designed to help graduates stay up to date with the latest gem and jewelry news and information.

	You will have continuous access to the entire program – including the assignments, GIA eLearning courses and previous years Continuing Education assignments and the multimedia archive – until the end of the calendar year. Each graduate who completes the Continuing Education Recognition Program will receive a certificate that displays their expertise and commitment to staying on top of gemological developments.

	“The word is out amongst our graduates and corporate education clientele about the value and importance of this program,” says Kate Donovan, Alumni Relations manager. “Relevance is key in a competitive market, and this program gives GIA graduates the opportunity to keep up the standard of education they worked so hard to achieve. Having access to the entire gemological course data that new GIA students are currently using is invaluable.”

	Be sure to sign up and complete all eight assignments by Dec. 31 to receive your Continuing Education Recognition Program certificate.

	Assignment 2: Indian Jewelry

	Assignment 1: The Diavik Diamond Mine

	Richard Lebreton, head of the surface geotechnical engineering team at Diavik Diamond Mine, located in the Lac de Gras kimberlite field in the far, frozen reaches of Canada’s Northwest Territories, discusses the obstacles he and his colleagues face as they try to keep the mine structure safe and stable.

	Assignment 2: Indian Jewelry

	GIA gemologists visit Indian jewelry manufacturers and retailers to learn about traditional gem-setting, gold carving and enameling techniques; gain insight into the state of manufacturing in India; and see first-hand the continued demand for these traditional styles of jewelry.

	Assignment 3: Australian Opal

	A team of GIA gemologists visited Australia’s famed opal fields in 2015 to observe the locations where Australian opals, of the world’s most popular gems and one of the birthstones for the month of October, are found.

	Assignment 4: Australian Sapphire

	Australia is one of the world’s most prolific sapphire sources. GIA’s team of field gemologists visited sapphire mining operations to see first-hand where and how this precious gem is recovered.

	Assignment 5: Colombian Emerald

	Assignment 5: Colombian Emerald

	Emerald, the beryl family’s most famous member, is treasured as the May birthstone. Among the world’s most prized emeralds are those that come from Colombia. Join GIA field gemologists as they visit this celebrated emerald source.

	Assignment 6: Sapphire Mining in Montana

	A team of GIA gemologists visit mining operations in Montana’s “Big Sky Country” to learn about sapphires mined there. Gold prospectors in the 1860s thought they were a nuisance (they plugged up their sluice boxes) – until Dr. George Frederick Kunz, of Tiffany & Co., determined them to be “sapphires of unusual quality.”

	Assignment 7: Heat Treatment of Montana Sapphires

	Chris Cooney, of Gem Mountain, Montana, explains the heat-treatment process to improve the color appearance of some Montana sapphires, which sometimes have a pale color or greenish, hazy cast.

	Assignment 8: Tennessee Shell Harvesting

	Assignment 8: Tennessee Shell Harvesting

	A GIA team made a recent visit to the Tennessee River to learn about the mussels that live in its murky waters and the mother-of-pearl they produce. This is an exceedingly beautiful material historically used to make buttons and “kaku,” pearl-culturing nuclei. In Parts 1 and 2, you’ll learn about the health of this industry and the area’s mussel population.

	Don’t miss this chance to learn more valuable and exciting information from GIA’s top experts. Find out more about GIA’s Continuing Education Recognition Program. You can also contact the GIA Alumni Association at (760) 603-4145 or email alumni@gia.edu. @chapter:34 @chapter:3 @chapter:34


# Publication Year: -
# Title: Books: The Art of Bulgari:La Dolce Vita and Beyond, 1950–1990
# Abstract: By Martin Chapman and Amanda Triossi, 174 pp., hardcover, illus., publ. by The Arts Museums of San Francisco/Delmonico Books/Prestel, 2013, $34.95

                      For those who associate Bulgari with vivid colored stone cabochons or antique Roman coins mounted in gold jewelry, Chapman and Triossi’s book is an eye-opener. The Art of Bulgari served as the catalog for the exhibition of the same name at the de Young Museum in San Francisco, intended to chronicle the succession of glamorous celebrities who have worn Bulgari from the dolce vita years of Italian cultural creativity through today. The authors also aim to trace the development of Bulgari’s creative aesthetic through compelling and sometimes surprising examples of its work. In both respects, they succeed.

The jewelry and luxury goods firm is so strongly associated with Rome that it may surprise readers to know that the founder, Sortirio Bulgari, opened his first shop in his native Greece. He later relocated to Naples, and finally to Rome in 1881, where the flagship store, opened in 1905, still stands at 10 Via Condotti.

Prior to World War II, the company operated as a traditional goldsmith shop, but thanks to Sortirio’s forward-thinking sons Costantino and Giorgio, Bulgari began to take a more contemporary direction. Jewelry inspired by Greco-Roman classicism, the Italian Renaissance, and the 19th-century Roman school of goldsmiths took hold, as Bulgari acquired important gemstones and created exclusive luxury pieces, including an emerald and diamond necklace commissioned by American socialite Brooke Astor.

In the post-war 1950s and ’60s, American movies were often filmed in Italy, where production costs were advantageous. As a result, many Hollywood stars fell in love with Bulgari’s bold new style, which featured large pieces set with colored gemstones. Most notable of these was Elizabeth Taylor, although Audrey Hepburn, Ingrid Bergman, Ava Gardner, and Gina Lollobrigida were also steady customers. Wealthy and influential socialites, including Barbara Hutton and Diana Vreeland, also became collectors.

Beginning with the 1950s, Chapman and Triossi show us the evolution, decade by decade, of Bulgari’s distinctive style. The use of color in so many Bulgari pieces stands out, but some gold and diamond jewels featured in this book, such as the Fireworks necklace and the Parentese parure, both from the Heritage Collection, are likewise dazzling.

The book devotes a chapter to pieces from Elizabeth Taylor’s Bulgari collection. Taylor is quoted as saying, “Undeniably, one of the biggest advantages of working on Cleopatra in Rome was [the Bulgari store].” It is clear how dearly she loved this jewelry, wearing her Heritage Collection platinum necklace with emeralds and diamonds to receive an Academy Award in 1966 and again when she was introduced to Queen Elizabeth II of England.

The Art of Bulgari also showcases whimsical pieces  that are relatively unknown. Such items include a gold measuring stick (1970), a silver-and-gold St. Moritz cigarette case (1977), a silver-and-gold tennis ball canister (1980), and a wonderful boat paperweight (1974) fashioned of sterling and gilded silver to look like a boat of folded paper. An exotic gold table clock with onyx, mother-of-pearl, and diamond (1980) is set off by two antique Chinese jade belt hooks.

The text is enhanced by excellent photography, with many jewels displayed in full-page plates. Original sketches of jewelry designs also add visual interest and insight, and photos of famous clientele wearing their Bulgari jewels abound. From magnificent bib necklaces and snake bracelet watches, to the whimsical Star-Spangled Banner series and ice cream cone brooches, this is a stunning look at Bulgari.

Chapman is a curator at the Fine Arts Museums of San Francisco, and Triossi, a jewelry historian and consultant, is curator of the Bulgari Heritage Collection. Together, the authors do an admirable job of presenting Bulgari’s history and cultural impact. @chapter:20 @chapter:2 @chapter:20


# Publication Year: 2023
# Title: Tubular Feature in a Natural Pearl
# Abstract: Figure 1. This 1.27 ct white semi-baroque pearl exhibited a typical platy structure when examined under magnification. Photo by Lhapsin Nillapat.
Recently, GIA’s Bangkok laboratory received a 1.27 ct white semi-baroque pearl for pearl identification service (figure 1). Under 40× magnification, the surface exhibited typical nacreous overlapping aragonite platelets (platy structure).

Figure 2. Left: RTX image taken along the pearl’s thickest direction showing a stacked internal structure that could be misinterpreted as a void typically observed in non-bead cultured pearls. Center: RTX image from the flat direction revealing a tubular feature in the center. Right: μ-CT image revealing multiple interconnected rounded voids.
Real-time microradiography (RTX) revealed a tubular feature like a twisted tunnel at the center of the pearl, surrounded by fine growth arcs. When observed along the pearl’s thickest direction, the feature resembled a void or cavity-like structure (figure 2, left), similar to those found in non-bead cultured pearls (“The microradiographic structures of non-bead cultured pearls,” GIA Research News, November 20, 2009). However, when viewed from its flat direction (figure 2, center), the elongated tubular nature of the feature was inconsistent with the voids observed in non-bead cultured pearls. This inconsistency was further supported by X-ray computed microtomography (μ-CT), which showed multiple interconnected rounded voids (figure 2, right). When exposed to X-ray fluorescence, the pearl displayed an inert reaction indicative of a saltwater environment.

Figure 3. Similar tubular features observed in three reportedly natural saltwater pearls weighing 0.25, 0.34, and 0.44 ct, respectively, sourced from Pinctada radiata mollusks from the waters of Bahrain.
While this was the first time the lab had encountered a client submission with such a structure, similar structures were previously documented in three reference pearl samples from GIA’s research database. The three were reported to be natural Pinctada radiata pearls sourced from the waters of Bahrain; they were baroque and weighed 0.25, 0.34, and 0.44 ct (figure 3). Those samples showed a similar elongated twisted tubular feature at their center in RTX and μ-CT scan imaging, which helped confirm the natural origin of the examined pearl.

Figure 4. The 3D models generated using μ-CT scans revealed the tunnel-like feature (red) suspected of being parasite remnants or evidence of parasitic activity within the pearl.
To further study this tubular feature, three-dimensional models were created using specialized software to render the μ-CT scan images (“New 3-D software expands GIA’s pearl identification capabilities,” GIA Research News, May 13, 2016). The results from these models clearly showed that the central structure consisted of an elongated twisted tube. Based on the tubular formation presented, the feature is suspected to be formed by a burrowing parasite trapped in the center of the pearl (figure 4; see video below). Parasites of various types have been observed in both saltwater and freshwater bivalves, and certain worms have been known to use bivalve mollusks as their hosts. Notably, marine bivalve mollusks tend to be more prone to parasitic intrusions than freshwater mussels (E. Strack, Pearls, Rühle-Diebener-Verlag, Stuttgart, 2006, p. 116). Therefore, the presence of such tubular features in saltwater pearls indicates the potential infiltration of worm larvae into the mollusks’ mantle. These larvae—either dead, alive, or hibernating—may have subsequently become encapsulated by the mantle epithelial cells, leading to the formation of a pearl sac and eventually the creation of a pearl.

	Tubular Feature in a Natural Pearl @chapter:11 @chapter:4 @chapter:11


# Publication Year: -
# Title: Spring 2012 G&G Lab Notes
# Abstract: Artificially Irradiated Type IIb Diamond
Type IIb Green Diamond, Natural and Synthetic
Diamond with Unusual Color Zoning
Large Emerald with Gota de Aceite Structure
Update on Artificial Metallic Veining in Manufactured Gem Materials
Shell-Nucleated Freshwater Cultured Pearls
Lazurite Inclusions in Ruby
A Coated Shell Assemblage

To view the full section, download the PDF above. @chapter:18 @chapter:1 @chapter:18


# Publication Year: 2016
# Title: Aurora Iris Agate
# Abstract: Figure 1. In transmitted light, this skillfully carved iris agate displays a scene reminiscent of an aurora. Photomicrograph by Nathan Renfro; field of view 5.28 mm.

	When solar wind interacts with the earth’s magnetosphere, spectacular multicolor light shows occur. This phenomenon is referred to as an aurora borealis in the Northern Hemisphere and an aurora australis in the Southern Hemisphere. This author recently examined an iris agate that provided a microscopic scene remarkably similar to an aurora (figure 1). The 1.67 ct carving seen in figure 2 was fashioned by Falk Burger (Hard Works, Tucson, Arizona). Burger took advantage of this quartz’s unique growth texture by carving the agate’s back, producing a wispy iridescent effect that is visible when using a point light source. Along the lower portion of the gem was a thin layer of crystalline quartz with a seam of pyrolusite dendrites between the crystalline quartz and microcrystalline iris agate. The combination of these layers gives the viewer the impression of an aurora occurring over a forest-rimmed frozen lake (see video at www.gia.edu/gems-gemology/aurora-iris-agate-carving).

	Figure 2. The 1.67 ct iris agate, shown here in transmitted light (left) and reflected light (right) was carved to showcase the dynamic nature of the iridescent colors. Photos by Kevin Schumacher. @chapter:18 @chapter:1 @chapter:18


# Publication Year: 1994
# Title: Emeralds from the Mananjary Region, Madagascar: Internal Features
# Abstract: Inclusions in emeralds from the Mananjary region in the eastern part of the island nation of Madagascar are reported and compared with inclusions in emeralds from other, especially African, localities. Although most of these internal features are similar to those found in emeralds from other schist-type deposits, Mananjary emeralds usually can be separated from emeralds from other localities by means of associations of certain mineral inclusions (especially talc, carbonates, amphiboles, and quartz) with specific types of fluid inclusions. @chapter:8 @chapter:0 @chapter:8


# Publication Year: 2002
# Title: New Chromium- and Vanadium-Bearing Garnets from Tranoroa, Madagascar
# Abstract: Pyrope-spessartine garnets from Tranoroa, in southern Madagascar, contain appreciable Cr and somewhat lower V contents. Although these elements are responsible for the color-change behavior of similar garnets from the nearby Bekily area, the Tranoroa samples show only a slight change in color appearance from day or fluorescent light (brownish purple-red) to incandescent light (purplish red). Characteristic internal features in the Tranoroa garnets include networks of rutile needles and strain patterns caused by anomalous double refraction. Additional inclusions are graphite, quartz, negative crystals, apatite, zircon, and monazite. One Cr-bearing spessartine from the same area is also described. @chapter:12 @chapter:0 @chapter:12


# Publication Year: 2023
# Title: Turquoise Planet Earth
# Abstract: An 84.90 ct sphere of Armenian turquoise measuring 23.70 × 23.88 × 23.91 mm displays a striking resemblance to planet Earth. Left: Diffuse fiber-optic lighting allows the face of the stone to be seen in full. Right: Pinpoint fiber-optic lighting creates an appearance of day and night cast onto Earth. Gifted to GIA’s colored stone reference collection by Gemfab CJSC. Photos by Britni LeCroy.
Armenia is not a widely known source of turquoise, but a recent donation to GIA’s colored stone reference collection proved that the country can produce high-quality, aesthetically pleasing stones. One of them, cleverly cut into an 84.90 ct sphere measuring 23.70 × 23.88 × 23.91 mm, bore an astonishing resemblance to planet Earth (see above). The natural brown matrix material mimicked the continents, while the greenish blue turquoise represented the oceans. Infrared spectroscopy showed that, like most gem turquoise, the specimen had been polymer impregnated, a treatment that makes the stone more durable. Additionally, no dye was detected. To accentuate its likeness to our planet, the sphere was photographed against “Musou Black,” marketed as the world’s blackest fabric and advertised to absorb 99.905% of all light. Precise placements of pinpoint lighting created various appearances of a sunlit Earth suspended in space. @chapter:0 @chapter:0 @chapter:0


# Publication Year: 1986
# Title: A Survey of the Gemstone Resources of China
# Abstract: The People's Republic of China has recently placed a high priority on identifying and developing its gemstone resources. Initial exploration by teams of geologists throughout China has identified many deposits with significant potential, including amber, cinnabar, garnets, blue sapphires, and diamonds. Small amounts of ruby have also been found. Major deposits of nephrite jade as well as large numbers of gem-bearing pegmatite dikes have been identified. Significant deposits of peridot are currently being exploited from Hebei Province. Lastly, turquoise rivaling the finest Persian material has been found in large quantities in Hubei and Shaanxi Provinces. @chapter:1 @chapter:0 @chapter:1


# Publication Year: 1999
# Title: Spring 1999 G&G Book Reviews
# Abstract: “Arab Roots of Gemology—Ahmad ibn Yusuf al Tifaschi’s Best
Thoughts on the Best of Stones”
Translated with comments by Samar Najm Abul Huda, 271 pp., illus., publ. by Scarecrow Press, Lanham, MD, 1998. US$45.00

“L’e Meraude: Connais-Sances Actuelles et Prospectives [The Emerald: Current and Prospective Knowledge]”
Edited by Didier Giard, 235 pp., illus., publ. by Association Française de Gemmologie [gemmes@animasoft.fr], Paris, 1998 (softbound; in French, with partial English translations). 350.00 FF (about US$57.00)

“The Great Encyclopedia of Precious and Decorative Stones”
By Nikodem Sobczak and Tomasz Sobczak, 422 pp., illus., publ. by National Science Publishers, Warsaw, 1998 (in Polish), US$20

“Larousse des Pierres Précieuses”
By Pierre Bariand and Jean-Paul Poirot, 287 pp., illus., publ. by Larousse-Bordas, Paris, 1998 (in French), 250.00 FF (about US$42.00)

“Standards & Applications for Diamond Report/Gemstone Report/Test Report”
By SSEF Swiss Gemmological Institute, 118 pp., illus., publ. by SSEF, Basel, Switzerland, 1998, US$65.00

To view the full section, download the PDF above. @chapter:17 @chapter:0 @chapter:17


# Publication Year: 2002
# Title: Rhodizite-Londonite from the Antsongombato Pegmatite, Central Madagascar
# Abstract: Londonite was approved as a new mineral species in 1999. This rare aluminum-beryllium borate is the cesium-rich analogue of rhodizite; the two end members can be separated only through quantitative chemical analysis. The only known source of gem-quality londonite is the Antsongombato pegmatite in central Madagascar, from which at least 300 carats of rhodizite-londonite have been faceted. The gemstones are colorless to greenish yellow, with an R.I. range of 1.689–1.691, S.G. of 3.34–3.42, and yellowish green fluorescence to short-wave UV. Internal features include partially healed fractures and conspicuous growth zoning that typically correlates to areas of anomalous birefringence. Some near-colorless rhodizite-londonite from Antsongombato has been irradiated to greenish yellow or yellow using X-rays. Both natural-color and irradiated rhodizite-londonite will fade on prolonged exposure to sunlight. @chapter:12 @chapter:0 @chapter:12


# Publication Year: -
# Title: GIA Researchers Evaluate ‘Light Performance’ and Diamond Cut
# Abstract: The GIA Cut Grades represented in these diamonds (from left, Poor, Good and Excellent) reflect how people see them. Any evaluation of cut quality should reflect what the eye sees. The term “Light Performance” has different connotations in the trade and is not used by GIA to describe diamonds. Kevin Schumacher/GIA

The phrase “light performance” gets a lot of loose use in the diamond trade. Terms such as brightness, brilliance, fire and scintillation are defined by various organizations with both clear and vague descriptions. The correlation of any of these properties to a diamond’s proportions are rather broad, while specific claims of better appearance are made for narrow ranges of proportions (particularly the “Ideal” cut for round brilliants).
Major deficiencies in a round brilliant’s appearance produced by extreme proportions have been understood for a century. Phenomena such as a fish-eye, dark center or dark mains that extend to the stone’s edge, produced, respectively, a too shallow pavilion, a too deep pavilion or a mismatch between crown height and pavilion depth. The discussion for more than 75 years has been focused on “proving” which proportions offer the best appearance.
But does “light performance” have an agreed-upon meaning? Just what does it mean?
In regard to diamond appearance, many would assume that high light performance means all observers will love the diamond. But how much of a part has human observation played in the development of any system for evaluating light performance in polished diamonds? In particular, do observers visually value the properties that are used in various approaches to exploring light performance?

This diamond has a well-distributed contrast of light and dark areas, forming a pattern that “performs” well while rocking and tilting. This dynamic aspect of light performance ‒ where the pattern itself changes as the diamond moves, yet continues with a good distribution of the pattern elements and resulting brightness ‒ is an important part of what the eye sees and its perception should be part of an evaluation of light performance. The angles and proportions of facets used to cut this diamond have been well known for decades to create diamonds that are attractive to most observers. Video by Nicole Phelan/GIA
How is light performance evaluated?
The most widely discussed method for evaluating light performance in recent decades uses a colored dome or cylindrical viewer, some with layers of colors. The colored dome or cylindrical viewer is used either as part of a device for viewing a diamond, or employed in a computer model with the 3D measurement (wireframe) of a diamond as input. This approach yields an image whose colored pattern reveals how the light that exits face-up and perpendicular to the table relates to the angles at which light enters the diamond. The pattern depends on both the proportions and symmetry of the diamond. It does not measure the amount of light exiting the diamond’s crown, and many implementations exclude specific evaluation of either fire or scintillation. There are various criteria for how much pattern difference is permitted within each grade range. Some users of this method include tilting the diamond, while others use only the face-up perpendicular position.
In all its variations, this approach assumes that the chosen standard addresses all issues regarding the balance of brightness, fire, contrast pattern and sparkle that are desirable in a diamond. None of the users of this approach have reported on human observations to verify that their conclusions make visual sense.
Another method uses an imaging spectrophotometer to obtain five images of the diamond at different distances from the light source. These images are analyzed for the amount of bright white light (described as brightness), colored light (described as fire) and differences among them (described as scintillation). This approach yields a measure of light exiting the diamond’s crown, but quantitative results are not presented. Instead, the three analyzed values are displayed on bar graphs relative to a database of thousands of previously measured diamonds of the same shape. The device does not permit tilting of the diamond relative to either the light source or detector. The question looms again, were any human observations conducted to verify that the three output values correlate to what people see?

This diamond has a very poor distribution of light and dark areas, forming a pattern that most find very unattractive. It also “performs” poorly while rocking and tilting. The strong, heavy “spokes” radiating from the center, surrounded at the outer edge by darkness, does not improve when tilted and the pattern itself hardly changes as the diamond moves. Large areas of concentrated darkness or dullness are a result of steeper crown and pavilion angles that the trade has avoided since they know those angles will create a poor looking diamond. Video by Nicole Phelan/GIA
Other factors that affect light performance
Some of the light performance information out there is very questionable. Polished diamonds return less than half the light energy that enters them, not “most” of it. Brighter does not indicate better appearance, because brightness is different than brilliance — both a mirror and a sheet of white paper return a lot of light, but neither is brilliant.
Human perception of brilliance requires a well-distributed contrast of light and dark areas. A diamond with good contrast and somewhat lower light return can look better than one with high light return and little contrast. Additionally, the diamond should also “perform” well while rocking and tilting (the dynamic aspect of light performance). The change in contrast and brightness is an important part of what the eye sees and should be part of an evaluation of light performance.
Personal taste is an important factor of perceived light performance. During our observation experiments, GIA found broad agreement on the displeasing aspects of diamond appearance, such as large areas of darkness, but noteworthy disagreement on what is most pleasing. Focusing on a particular diamond appearance, such as Hearts & Arrows, to the exclusion of all others leaves little room for personal preference. Of course, GIA feels that information provided to a third party needs to be thorough and not just focused on one aspect of a diamond.
Note that light performance in many other systems does not include the impact of other important factors that provide comprehensive information about a diamond. Weight ratio (e.g. thick girdles), durability (risk for chipping) and craftsmanship (which includes symmetry and polish quality) are also very important criteria that should not be ignored in evaluating cut.
Coming back to the original question: what does light performance really mean? Since diamonds are something we wear to show to others, the answer should be tied a diamond’s visual appeal. Physics may say that a certain diamond under specific conditions returns more light than another, or has more fire than another, but do you and I see these things? Light performance should mean that computer modeling, instrumentation or any other methods that claim to evaluate a certain diamond and assign a value or a grade should be linked to what we actually see.
GIA continues to avoid the use of the term “light performance” because of the ambiguity with which the trade uses it. @chapter:41 @chapter:1 @chapter:41


# Publication Year: 2022
# Title: Large Diamond Inclusion in Diamond
# Abstract: Figure 1. Trigons seen on a diamond crystal inclusion visible through the crown of a round brilliant diamond. Photomicrograph by A’Dhi Lall; field of view 2.11 mm.
Recently, the authors examined a 2.01 ct Faint green round brilliant diamond with a fascinating diamond crystal inclusion that displayed a transparent, ghost-like appearance. Due to the large size of this nearly invisible crystal, the stone was given a clarity grade of SI2.

Figure 2. Strain between the host diamond and the diamond inclusion is revealed by the interference colors in cross-polarized light. Photomicrograph by A’Dhi Lall; field of view 13.55 mm.
Photomicrography was used to document the features of this inclusion. Triangular etch features, also known as trigons, were seen on the inclusion (figure 1). These are typically natural growth markings of diamonds, confirming the inclusion as diamond. The diamond crystal inclusion appeared to have sharp and easily recognizable faces. Images with cross-polarized light show strain between the inclusion and the host diamond (figure 2). A DiamondView image also reveals the diamond crystal inclusion (figure 3).

Figure 3. DiamondView image of the diamond inclusion in the diamond host. Image by Luthfia Syarbaini.
Generally, the beauty and value of a diamond increase with the absence of inclusions. Yet the presence of a diamond inclusion gave this diamond a certain distinction, which in the authors’ opinion added to its beauty and value. @chapter:29 @chapter:1 @chapter:29


# Publication Year: 2016
# Title: Large Colorless HPHT Synthetic Gem Diamonds from China
# Abstract: Figure 1. A factory in Shandong, China, is producing a large number of colorless HPHT synthetic diamonds for the jewelry industry. These crystals have typical cuboctahedral morphology and weigh up to 3.5 ct. Photo by Jianxin (Jae) Liao.

	High-pressure, high-temperature (HPHT) technology for gem diamond synthesis has made rapid progress in the last few years. It is now being used to produce many melee-size diamonds around 2–3 mm in diameter and large colorless single crystals, all with significantly improved quality and growth rate. One Russian company is reportedly growing multiple large, gem-quality colorless diamond crystals in a single run (U.F.S. D’Haenens-Johansson et al., “Large colorless HPHT-grown synthetic gem diamonds from New Diamond Technology,” Fall 2015 G&G, pp. 260–279). Here we report on large diamond crystals manufactured using a similar technology by Jinan Zhongwu New Materials Co. Ltd in Shandong, China.

	We visited the Chinese factory in early March 2016 and obtained 50 crystals (figure 1). The crystals were examined using the instrumentation and techniques applied to all diamonds submitted to GIA for grading; all exhibited the typical characteristics of HPHT growth and were identified as synthetic. These were basically colorless, with only a few metallic inclusions observed. These crystals showed typical cuboctahedral morphology, with well-developed {100}, {110}, and {111} growth sectors and a weakly developed {113} sector. The crystals we obtained ranged from about 0.5 to 1.2 ct each. Absorption spectra in the infrared region showed they were type IIa diamond, but trace absorption from boron was detected (2800 cm–1). Detailed gemological and spectroscopic analyses are ongoing and will be reported separately.

	According to the manufacturer, large quantities of gem-quality colorless and blue diamonds are produced in this factory, in sizes up to 3.5 ct each. While the total production volume remains unclear, it is undoubtedly significant, and capacity is likely to expand in the near future. This strongly suggests that even more large HPHT synthetic diamonds will be introduced into the jewelry industry. @chapter:9 @chapter:1 @chapter:9


# Publication Year: -
# Title: Rubies Reportedly from Mozambique
# Abstract: Attractive new rubies reportedly from northern Mozambique have begun to appear on the Thai gem market. The stones resemble rubies from Winza, Tanzania, but this study shows they can be distinguished by microscopic examination. @chapter:30 @chapter:0 @chapter:30


# Publication Year: 2024
# Title: Wedding ring industry trends Germany
# Abstract: The outbreak of the coronavirus has led many couples to postpone their weddings. The wedding industry in Germany has seen a decline in numbers compared to previous years due to economic uncertainties. Consumers have become more cautious in their spending habits, affecting the wedding ring market as well. GZ Goldschmiede Zeitung conducted a survey to understand the current situation and trends in the wedding ring industry, highlighting four main trends:

1. Everything is contracting.

The decrease in weddings has naturally led to a decrease in the demand for wedding rings. Coupled with economic inflation, consumers are spending more cautiously. It is estimated that the number of businesses producing wedding rings has decreased by around 10% to 15%. In July 2023, which historically sees the most weddings in Germany, there were about 42,100 registered marriages compared to approximately 51,000 in the same month in 2022. Overall, in 2022, there were about 390,000 registered marriages, while in the first seven months of 2023, there was an 8% decrease from 213,000 couples to 196,000 couples. The COVID-19 situation has caused many couples to postpone their weddings to 2022 instead.

According to a survey by Weddyplace, the average expenditure on weddings in Germany is around €14,000, which is higher than the pre-COVID average by 40%. Regarding the cost of wedding rings, 62% of respondents are willing to pay between €1,000 to €4,000.

2. Everything is more expensive than before.

The cost of goods has risen, including the various metals used in making wedding rings. Towards the end of November 2023, the price of gold per gram surged by over 8.6% compared to the beginning of the year. For buyers with budget constraints, it becomes necessary to reduce the width of the rings or opt for cheaper materials. The most popular metals for making wedding rings among Germans are gold, symbolizing profound love, followed by platinum, rose gold, and white gold. The value of a ring depends on the mix of these metals. Compared to gold, platinum is cheaper. Therefore, wedding rings made of platinum are among the top choices for buyers.

3. Everything is happening faster than before.

According to the survey results, over 50% of couples spend about 2 weeks choosing wedding rings, while 23% spend about 1 month. However, it's found that 1 in 3 couples spend only 1 week in finding and choosing wedding rings. The decision-making process for choosing wedding rings has become easier and faster. Couples can now design their wedding rings online according to their preferences, which is different from buying at jewelry stores where exchanging information with sales staff and making appointments often takes more than 1 hour. Many couples prefer designing their unique wedding rings with personalized inscriptions. Women's wedding rings often feature small diamonds, and typically, the waiting time for rings ordered online is no more than 6 weeks before they are delivered.
4. Everything is increasing.

Before the wedding ceremony, many couples often engage and announce their engagement beforehand. Engagement without an engagement ring is like a wedding without the bride's flower bouquet. According to Responsio's survey, 78% of engagements involve an engagement ring. Jewelry stores use this as a way to attract customers to come back and purchase wedding rings. Fabian Meister, a jewelry manufacturing industry expert, mentioned that satisfied customers often return to the store. Ordering both the engagement ring and wedding ring from the same store is not uncommon. From mydays' survey, 85% of German men are willing to pay between 500 to 1,000 euros for an engagement ring, 13% are willing to pay between 1,000 to 2,000 euros, and 2% are willing to pay more than 2,000 euros. On the women's side, they often reciprocate by giving gifts that complement the engagement ring, such as earrings, keychains, bracelets, or watches. These gifts are not just tokens for the joyful time but also considered family assets. The trend of giving such gifts is increasing, depending on various occasions like the first child's birthday or wedding anniversary celebrations. @chapter:32 @chapter:3 @chapter:32


# Publication Year: 2014
# Title: Composite Coral Veneer Glued to Artificial Matrix
# Abstract: Figure 1. These 14 ornaments, represented as red coral products, consisted of a coral veneer glued to a matrix. The ten bangles (top) weigh 37.34–57.43 g, and the four snuff bottles (bottom) range from 121.95 to 145.07 g. Photo by Haibo Li.

Red coral, one of the most precious organic gems, has become increasingly popular in the Chinese jewelry market. With natural coral resources being depleted, ornaments of large size and high quality are becoming even more valuable. As a result, the market for treated red coral and imitation products is rapidly growing.
Composite red coral normally consists of coral fragments glued together with cement compounds. In 2010, the National Gemstone Testing Center Gem Laboratory in Beijing tested one bangle that was represented as red coral (Summer 2010 GNI, pp. 158–159). Because the client did not allow the lab to take a powder sample, further testing was restricted. There was some concern about whether the bangle had an artificial matrix, but this could not be determined without destructive tests.
Recently, the NGTC received 10 bangles and four snuff bottles (figure 1) presented as red coral. The bangles resembled the one tested in 2010. Each of the 14 pieces was covered with a very thin surface layer of red coral. The composition of the material below this coral veneer was analyzed.
Magnification revealed the boundaries between the coral fragments and the cement compounds, which tended to be recessed (figures 2 and 3). This clearly demonstrated that the veneer was composite red coral. The coral fragments had a vitreous luster and showed wavy growth patterns typical of natural coral. No growth patterns were seen in the cement compounds except for air bubbles.

Figure 2. Left: A close-up of a bangle with coral veneer. Right: The bangle’s inner surface is covered with rectangular coral slices, but gaps filled with cement compounds are still visible. Photos by Haibo Li; magnified 6.5×.

Figure 3 A: Reflected light showed the difference in luster between the cement compounds and the coral fragments; magnified 10×. B: Under transmitted light, air bubbles can be found in the cement compounds; magnified 20×. C: The boundary between the matrix and the composite coral veneer is very clear and sharp; magnified 10×. D: The fluorescence reaction of the same sample under short-wave UV. Photomicrographs by Haibo Li.
Whitish material seen inside the neck of the bottles was identified as an artificial matrix. The composite red coral veneer, which was only about 1–2 mm thick, had been glued to the surface of the whitish matrix. Under a short-wave UV lamp, strong blue-white fluorescence from the cement compounds and the matrix was visible (figure 3).
Micro-infrared spectrometry (with 4.0 cm–1 resolution and 64 scans in the 675–4000 cm–1 range) identified the cement compounds as epoxy resin (figure 4A). Two different kinds of artificial matrix material were detected: ethyl cyanoacrylate (figure 4B) and alkyd synthetic resin mixed with carbonates. The main component of the carbonates was established as calcite by subtracting the spectra (figure 4C). The calcite could have come from the manufacturing process of the composite red coral.

Figure 4. A: The IR spectrum of the cement compound in one of the bangles identified it as epoxy resin. B: The IR spectrum of the artificial matrix material in one of the snuff bottles indicated ethyl cyanoacrylate. C: The artificial matrix material in the other three snuff bottles was identified, by subtracting IR spectra, as alkyd resin mixed with carbonates.
The SG of the synthetic resin was about 1–2 g/cm3, much lower than that of red coral (2.65 g/cm3). Carbonates could have been added to the matrix to make it heavier and approximate the heft of coral. The snuff bottles all had similar size but different weights. The three that contained alkyd resin mixed with calcite, which has a relatively high SG, weighed 140–145 g. The matrix in the fourth snuff bottle was ethyl cyanoacrylate, which has a lower SG than calcite. As a result, it only weighed 121 g.
In today’s market, oversized red coral products are often constructed from an artificial matrix. After the matrix is shaped, a veneer of red coral fragments is glued to its surface. This makes it easier to manufacture larger ornaments while preserving natural coral reefs. Combining magnification and UV fluorescence observation with infrared spectrometry, we can identify composite coral assemblages quickly and effectively. @chapter:54 @chapter:4 @chapter:54


# Publication Year: -
# Title: Geologist’s Newest Mission: Share the Love of Colored Gemstones
# Abstract: “You’ll always be learning,” says Robert Gessner. “You’ll never know it all, and our industry is always growing and changing.” Gessner, a colored stone geologist who earned his GIA GG after more than a decade of working in Africa’s mines, is pictured underground in a Zambian emerald deposit in 2014. Photo by Vincent Pardieu/GIA

“Adventure is in my blood,” says Robert Gessner, a GIA Graduate Gemologist (GG) and Cape Town-born geologist who is the owner of Gessner Gems, a sourcing and curatorship firm for colored stones.

Gessner’s parents are of European descent – his maternal grandparents were Dutch diplomats who retired in South Africa, and his father’s family came from Germany before settling in Mozambique. When the Gessners married and started a family in South Africa, they never stopped exploring.

“I was fortunate growing up in a family that loved the outdoors and travel,” says Gessner, the eldest of four children. “By the age of 16, I’d traveled most of South Africa. We were always seeing something new, and it became etched on my soul. Now, there is no adventure to a new destination that I’d pass up easily. I love to meet new people, be exposed to their culture and see their country’s beauty.”

The family’s shared enthusiasm for exploration extended to the natural world.

“My earliest exposure to rocks and minerals was through monthly magazine supplements that my mom purchased from our local newsstand,” Gessner says. “They included a mineral and gemstone in a little display box, and as the months went by, the file of information about our earth, rocks and minerals – as well as the collection of specimens itself – grew into an impressive display. The beauty, variety and perfection of each gem had me hooked.”

Though his family had lived and traveled around South Africa, it wasn’t until college at the University of Cape Town that Gessner says the world truly opened up for him. He graduated with a Bachelor’s degree in geology in 2002, and said the discipline gave him “direction, a goal and access to a professional career.”

A self-described “eternal optimist,” Gessner submitted his near-empty resume to a local recruiting agency. Within weeks, he was contacted for a position as a geologist in Tanzania and accepted right away.

“It turned out to be the early years of the company that became Tanzanite One, the biggest, most technological colored gemstone miner and supplier of tanzanite to the world,” he says.

“My favorite thing about my career has been seeing the beauty of the finest gemstones and specimens and hearing stories from the owners who display them,” says Robert Gessner, inspecting a piece of tanzanite rough. He recently joined William Noble Rare Jewels as a colored gemstone specialist, and owns Gessner Gems, which specializes in sourcing and curating colored gemstones. Photo by Brendan Laurs/GIA
Some of Gessner’s new colleagues were earning their Graduate Gemologist diplomas through GIA’s Distance Education program, and he was intrigued. “It was the first time I’d heard of GIA,” he says. “I wanted to get involved.” He earned his Accredited Jewelry Professional diploma in 2008.

Gessner spent six and a half years in Tanzania before joining Gemfields PLC’s Kagem Mine in Zambia, working another six and a half years there.

“After 13 years of colored gemstone mining and exploration in East Africa, I was looking for my next opportunity,” he says.

Gessner started with a trip to the United States – his first ever – in 2015 for the Tucson gem and mineral shows. As a GIA alumnus, he knew about the Alumni Association’s annual dance party, and he knew he would have a chance to network and discover new paths within the industry.

“It was life-changing,” he says. “It was a 10-year reunion for me, meeting with all the field gemologists, scientists, writers and editors and professionals from our industry whom I had hosted, met and gotten to know in the mines.”

As a specialist in African colored stones, such as tanzanite, tsavorite and Zambian emeralds, investigating gemstones from Southeast Asia and South America also piqued his interest.

“Seeing all the gemstones and minerals from around the world lit a spark to learn all about them,” he says. “For continued career growth, studying at GIA was a no-brainer.”

Robert Gessner’s marriage to Los Angeles designer Melissa Spencer, GIA GG, began two years after the pair’s unexpected meeting at the GIA Alumni Association dance party. “It was love at first sight,” says Gessner, celebrating with Spencer on their March 2017 wedding day. Photo by Trent Bailey. Courtesy of Robert Gessner and Melissa Spencer
But the life-changing moments in Tucson didn’t stop with professional and academic changes. He met a Southern California jewelry designer named Melissa Spencer at the alumni dance party and after just a few dances, Gessner – who was being groomed for a position as general manager of Gemfields – knew he would not be returning to Africa.

“When you know, you know,” he says. “There was an immediate connection, like the stars and galaxies aligned. We have been inseparable since then. Our meeting at the GIA Alumni Association party was meant to be and changed our lives.”

Gessner returned to Zambia the next week and resigned from Gemfields. He also enrolled in GIA’s Graduate Gemologist program in residence at Carlsbad – much closer to Spencer, a GIA GG who was living in Los Angeles. Gessner graduated from GIA in March 2016, and married Spencer in March 2017.

“I enjoyed every single moment, particularly while in residence,” he says. “GIA’s practical and theoretical education platform and resources, including the staff and library, are world-class. The lab classes and practical work are vital, and supplemented by the literature and theory, they lay the foundation for a career. The relationships and friendships that I made there – and continue to make through GIA – helped equip me for success.”

Gessner Gems has just turned two years old and Gessner is thrilled to connect clients with fine colored gemstones from around the world.

“I share knowledge about gems with each client – its source, if known, what makes it different from other sources, if and why the gem is treated, and the romance of its geological origins in describing its rarity,” he says.

In addition to his own business, Gessner has recently accepted a position as a colored gemstone specialist with William Noble Rare Jewels in Dallas, Texas. He has also begun writing for trade publications, including GemGuide and AGTA’s Prism magazine.

In the same way that geology – and eventually, gemology – opened doors to learning and adventure around the globe, Gessner hopes that sharing his knowledge will open doors for others.

“I want to help take colored gemstones mainstream,” he says. “I want the public to know so much more about colored gemstones, to share the excitement and passion.” @chapter:17 @chapter:0 @chapter:17


# Publication Year: 2018
# Title: Update on the Green Dragon Demantoid Mine in Namibia
# Abstract: Figure 1. Namibian demantoid retrieved from the Green Dragon mine and preserved in its host rock. Photo by Albert Salvato.
According to Stephan Reif, Namibia’s Green Dragon mine is the largest continuously operating demantoid deposit. Green Dragon has a complete mine-to-market approach, handling everything from mining, ore processing, sorting, cutting, and grading to wholesale. They mainly supply the European market through Vienna and the Asian market through Hong Kong.

The mine was discovered in a remote part of southern Namibia in the 1990s and has been producing since the mid-2000s. In 2017, Green Dragon received a 25-year mining license for the deposit, offering stability as an incentive to invest in the mine. In the near future, mining will be scaled up and production will increase. This will provide a more consistent and attractive supply for buyers in the trade. As part of the 25-year mining lease, Green Dragon has committed to supporting the local communities.

Operations at the Green Dragon Mine
Stephan Reif provides an update on the activities at southern Namibia’s Green Dragon demantoid mine.
Namibian demantoid mining is highly mechanized, using heavy equipment to extract the green garnets from their host rock (see figure 1). Monthly production varies between 15 and 20 kg. Of that, a little over 10% is considered gem quality and goes for faceting.

Color ranges from yellowish green to bluish green, and some darker brownish greens are also found. Demand for certain colors varies, but at the moment the yellowish “golden” colors are in highest demand by designers. For Reif, the ideal Namibian demantoid is a slightly bluish green gem full of fire and brilliance.

Figure 2. The cutting and polishing of Namibian demantoid should emphasize the material’s lighter color and high dispersion. Photo by Albert Salvato.
The combination of lighter color and very high dispersion sets Namibian demantoid apart from other green garnets. These properties also depend on the quality of cutting and polishing (figure 2), something Green Dragon has focused on in recent years by having their in-house lapidaries and quality control perform to a higher standard. Because clarity, color, and calibration standards are so tight, the yield is only around 9%.

Most of the production is in melee and small calibrated sizes, with fine singles being extremely rare. Fine-quality melee is in very high demand in Europe at the moment, especially in the 4.0–6.5 mm range. In recent years, the demand for very small melee (1–2 mm) has increased substantially. Larger exceptional pieces typically go to Asia. @chapter:17 @chapter:0 @chapter:17


# Publication Year: 1981
# Title: San Carlos Peridot
# Abstract: Each year basalt-topped Peridot Mesa, on the San Carlos Apache Reservation, is a major source for thousands of carats of gem-quality peridot in sizes suitable for use in modern jewelry.  Marketed throughout the world, San Carlos material is often confused with, and sold as, peridot from localities that are better known and documented. Peridot Mesa resulted from a single volcanic eruption and basalt flow over an already existing conglomerate base; it is thought to be of late Tertiary or Quaternary age. The peridot is found in irregularly shaped nodules within the basalt. The gemological properties and color range of these Arizona gems suggest an olivine that is rich in the magnesium forsterite end member. Inclusions documented are chromite, chromian spinel, negative crystals, "lily pad" cleavages, glass blebs, chrome diopside, biotite, and smoke-like veiling. @chapter:6 @chapter:0 @chapter:6


# Publication Year: -
# Title: Winter 2011 Gem News International
# Abstract: Colored Stones and Organic Materials
	            Chondrodite from Mahenge, Tanzania
	            Blue Dolomite from Colombia
	            Fluorite from Namibia
	            Common Opal from Laverton, Western Australia
	            A Bicolor, Bi-Pattern Hydrophane Opal
	            Chatoyant Quartz with Cinnabar Inclusions
	            Quartz with Acicular Emerald Inclusions
	            Quartz Carving with Inclusions of Izoklakeite
	            Update on Ruby and Sapphire Mining in Pakistan
	            Vanadium-Bearing Color-Change Sphene from Pakistan/Afghanistan
	            Cobalt Blue-Colored Spinel from Khuoi Ngan, Vietnam
	            Trapiche Spinel from Mogok, Myanmar
Synthetics and Simulants
	            "Cat's-Eye Pearls": Unusual Non-Nacreous Calcitic Pearl Imitations
	            Large Synthetic Quartz
Treatments
	            Sugar-Acid Treatment of Opal from Wollo, Ethiopia
Conference Reports
	            32nd International Gemmological Conference
	            2011 NAG Institute of Registered Valuers Conference

To view the full section, download the PDF above.

	DATA DEPOSITORY

Fluorite from Namibia - Additional Spectra
Trapiche Spinel from Mogok, Myanmar - Additional Spectra
	January 9, 2012 @chapter:14 @chapter:0 @chapter:14


# Publication Year: -
# Title: The Timeless Allure of Art Deco
# Abstract: Tutti Frutti (bold color contrasts using carved gemstones) dazzles in this bracelet, brooch, and lapel watch by Mauboussin.  Jewelry courtesy of Kathryn Bonanno.

                      The Roaring Twenties – It’s a time that still fascinates us.

Autos, the radio, the telephone, and the motion picture became cultural fixtures. Skyscrapers sprung up in major cities. Jazz rang from speakeasies in Harlem. Charles Lindbergh made the first non-stop transatlantic flight. F. Scott Fitzgerald, Ernest Hemingway, Coco Chanel, Duke Ellington, Babe Ruth, and Charlie Chaplin commanded the cultural stage, their fame fueled by the rise of the mass media.

The role of women was also changing. Entering the workforce en masse during World War I, women gained the right to vote in 1920. Flappers – women who wore short dresses and short hair – were the new standard bearers of fashion, shocking society with their scandalous behavior. And they wanted a new style, something that was not like the frilly, traditional jewelry of the Edwardian and Art Nouveau eras.

Such was the setting for the arrival of Art Deco – a style that celebrated the machine age. Sleek ocean liners, streamlined trains, and towering skyscrapers were favorite images to express this: they symbolized prosperity, and progress, and the belief that technology was the cure for all ills.

The term “Art Deco” – the period lasted from the 1920s through the 1930s – came from Exposition Internationale des Arts Decoratifs et Industrials Modernes, an exhibition of decorative arts held in Paris in 1925. Jewelry was one of the featured items, and the judges selected geometric, linear pieces that celebrated modern industry.

	This Art Deco poster of a train conveys the power of technology and progress.
To give objects a futuristic look, Art Deco artists used vertical lines and geometric shapes (arcs, circles, triangles, squares, rectangles, etc.) in repetitive patterns. The Chrysler Building in Manhattan is a classic example of Art Deco architecture, and features a number of these design elements.

	The Chrysler Building is an Art Deco masterpiece.
Jewelry designers were very much a part of the Art Deco movement. Departing from the organic curvilinear flourishes that belonged to the earlier movement, Art Nouveau, these designers embraced the vertical line and simple, repetitive geometric patterns. The purpose was to evoke elegance and sophistication.

Art Deco jewelers used platinum and white gold, geometric shapes, and vivid color, contrasts to capture the spirit of the time. Diamond cuts in geometric shapes such as the baguette, triangle, trapeze, and half-moon became popular in Art Deco jewelry.

	Art Deco chandelier earrings made with platinum, emeralds, sapphires, and diamonds.
Advances in stone cutting allowed jewelers to make complex pieces, like this platinum, sapphire, and diamond pendant/brooch shown below.

	Brooch courtesy of Frank Goodman & Son, Los Angeles, CA.
A significant event in the Art Deco movement was discovery of King Tut’s tomb in 1922. Egypt’s art and architecture were exotic – fresh inspiration to artists schooled in old-world masters like Michelangelo and Rembrandt – and Art Deco practitioners readily borrowed motifs from it and other ancient civilizations that were being unearthed.

	Buckle courtesy of Ginger Moro.

		Art Deco artists were simultaneously taking from the past and looking to the future. This was a unique combination, and created a distinctive style that gripped the imagination of the public.

		Robert Ackermann, instructor of Jewelry Manufacturing Arts, GIA, Carlsbad.

The timeless beauty of Art Deco and its promise of a bright future is what captivated the flappers – and it still speaks to us. F. Scott Fitzgerald poetically expressed this sentiment in The Great Gatsby: “Gatsby believed in the green light, the orgastic future that year by year recedes before us. It eluded us then, but that’s no matter—tomorrow we will run faster, stretch out our arms farther. . . So we beat on, boats against the current, borne back ceaselessly into the past.”

Tips for designing and selling Art Deco jewelry

		Art Deco was defined by the vertical line and repetitive geometric shapes. Use them to design Deco-inspired pieces. Let your customers know how these design elements create a sleek and sophisticated look.

		Art Deco jewelry often has dramatic color contrasts. Perhaps this was an expression of optimism towards the future, or a welcome change from the pastels of the Art Nouveau era and the typical absence of colored stones in most Edwardian-Era jewelry. Use of bold, contrasting colored gemstones or enamel in your pieces can evoke the Art Deco style.

		Art Deco artists freely borrowed design elements from ancient cultures. The contrast of the modern and the old made for fascinating works. Customers are likely to find this interesting. You can also incorporate ancient motifs to add pizzazz to your designs. @chapter:20 @chapter:2 @chapter:20


# Publication Year: 2022
# Title: Mercury Free Mining Pilot Program
# Abstract: Figure 1. Gold and dense black sands in a traditional wooden batea, shown by a Colombian miner at Oro Verde. Typically, mercury is used to separate the two materials. Photo courtesy of Toby Pomeroy.
In late 2021, Mercury Free Mining (MFM), the Alliance for Responsible Mining (ARM), and GIA joined with Peruvian artisanal and small-scale gold miners (ASGM) to launch a new program intended to find alternatives to mercury in gold mining. The partners are bound in recognizing the reliance on artisanal and small-scale gold mining to produce major quantities of an extremely valuable commodity. This situation unfortunately perpetuates the leading cause of anthropogenic mercury pollution. The pilot program aims to proactively develop mercury alternatives in two gold mines, increasing their sustainability, building a traceable ASGM gold supply, and acting as a major leap in the MFM research team’s understanding of how we can ultimately eradicate mercury in gold mining.
Mercury Free Mining, the program lead, is a nonprofit organization founded by Toby Pomeroy, a lifelong goldsmith, jeweler, and passionate advocate for responsible sourcing. Founded in 2019 with the mission of eradicating mercury, MFM has been building a community of jewelers supporting efforts to provide the nearly 20 million ASGM with efficient and nontoxic mercury alternatives where presently unavailable.
MFM’s research and deployment team, led by the author, a geometallurgist, fosters novel sociotechnical solutions to address the issues facing ASGM with a focus on finding suitable mercury alternatives. This is a challenge. Gold is nonreactive to most chemicals (mercury being one of the only exceptions) and coincides with dense black sands that are difficult to mechanically separate (figure 1). The team’s methodologies rely upon the miners’ desire to maximize earnings by recovering more gold from the raw ores while also minimizing harmful social, health, and environmental side effects. Currently, reliable information about implementing mercury alternatives that are more effective and less harmful is scarce. Without this, miners have no choice but to rely upon a multi-generational neurotoxin in order to earn an income (figure 2).

Figure 2. In this photo from November 2020, Kenyan miners in Kakamega County press amalgam in a pan to remove excess water. Amalgam is a mixture of mercury and gold produced by adding mercury to concentrated gold ores. This method puts miners in direct contact with mercury, a potent neurotoxin that can be absorbed through the skin. Photo courtesy of Ruth Epwoka.
GIA granted $50,000 to jumpstart the pilot. Since then, MFM has collaborated with ARM engineers and Peruvian miners to collect representative mineral samples for use in testing a suite of innovative gold concentrators. MFM is partnering with six mineral processing experts to evaluate their respective technologies based on key performance indicators such as throughput, gold recovery, and concentration ratio. Spread across three continents, the testing will evaluate a large swath of potential mercury alternatives, helping to gather critical information on how different processors are suited for various gold ores (figure 3). This stage of the project will draw from advanced engineering and science to perform thorough analyses in an accurate and timely manner.

Figure 3. Miners wash the gold ores and use a sluice to collect gold within the slurry. Sluices are one of the most common tools used in artisanal and small-scale mining to concentrate gold. This simple configuration can capture ~20–70% of gold based on ore type, water flow, feed rate, and other specifications geometallurgists determine through research. Photo courtesy of Ruth Epwoka.
Following the testing, the results will be holistically synthesized by the MFM research team with respect to the many complexities of the miners’ unique situations. This will include a mercury comparison to understand the true viability for the miners to adopt an alternative. Stakeholder discussions will then determine whether the miners ultimately decide to adopt one of the mercury-free technologies. If so, the team will help implement the transition to mercury-free methods and conduct observational research to better define the impact on the health of miners and their communities.
The completion of this pilot program in 2022 will mark a turning point in MFM’s ability to minimize the global impacts of mercury by having a tested and verified framework that can translate to additional mercury elimination projects as MFM expands. Following the pilot, the MFM team will publicly release the first report documenting the research process and results in complete detail. This and future reports can be used freely by miners and organizations to enhance the ability to safely source gold. For those interested in learning more, collaborating, or using these methods elsewhere, please contact the author. @chapter:50 @chapter:3 @chapter:50


# Publication Year: 2013
# Title: Stellate Zircon Inclusions in Vivid Purple-Pink Morganite
# Abstract: Figure 1. Stellate clusters of zircon needles were observed in this purple-pink morganite. Vertical field of view 0.58 mm. Photomicrograph by Nathan Renfro.

              The Carlsbad laboratory recently examined a 4.95 ct vivid purple-pink morganite (figure 1). In addition to its saturated color, the stone was particularly noteworthy because of the inclusions it contained. Microscopic examination revealed numerous stellate inclusions, each with many delicate tapered legs.

Gemological properties revealed an RI of 1.577–1.583 and a hydrostatic SG of 2.73. It did not show fluorescence under either long- or short-wave UV. All of these properties were consistent with beryl, which was further confirmed by FTIR and Raman spectroscopy.

Inclusions in the stone showed an interesting starburst pattern, with thin needles radiating from a central point of nucleation. Viewed with polarized light, the needles exhibited birefringence. A sub-adamantine luster was observed where some of the needles broke the surface (figure 2). Raman spectroscopy identified the inclusions as zircon, consistent with our initial observations. Zircon inclusions are occasionally found in pegmatitic beryl, but they usually occur as prismatic or rounded crystals that cause damage to their host due to zircon’s relative instability (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, ABC Edition, Zurich, 1986, p. 197).

	Figure 2. The needle-like zircons showed a sub-adamantine luster when examined using reflected light. The largest surface-breaking needle measures approximately 10 microns in the longest cross-sectional direction. Photomicrograph by Nathan Renfro.
In addition to the zircon clusters, the stone also contained fluid inclusions, transparent crystals, particulate clouds, and singular needles. The distinctive morphology of the zircon inclusions, coupled with the vivid purple-pink color, create a rather unique gemstone. @chapter:26 @chapter:0 @chapter:26


# Publication Year: 2007
# Title: Winter 2007 G&G Book Reviews
# Abstract: “Jewels: A Secret History”
By Victoria Finlay, 472 pp., illus., publ. by Ballantine Books, New York, 2006. US$25.95

“Fine Minerals of China: A Guide to Mineral Localities”
By Guanghua Liu, 366 pp., illus., publ. by AAA Minerals AG, Switzerland, 2006. US$148.00

“The Jewelry Handbook: How to Select, Wear & Care for Jewelry”
By Renée Newman, 177 pp., illus., publ. by International Jewelry Publications, Los Angeles, 2007. $19.95

“The Pink Pearl: A Natural Treasure of the Caribbean”
By Hubert Bari after the text by David Federman, 173 pp., illus., publ. by Skira Editore S.p.A. [www.rizzoliusa.com], Milan, Italy, 2007. US$58.00

“Opal: The Phenomenal Gemstone”
By J. Clifford, P. Clifford, A. Frazier, S. Frazier, B. P. Gaber, C. J. Gaber, G. Neumeier, and G. Staebler, Eds., transl. by G. Neumeier, 108 pp., illus., publ. by Lithographie LLC, East Hampton, CN, 2007, US$40.00

“Namibia, 2nd Ed.”
By L. von Bezing, R. Bode, and S. Jahn, 856 pp., illus., publ. by Bode Verlag [www.bodeverlag.de], Haltern, Germany, 2007, US$158.00

To view the full section, download the PDF above. @chapter:28 @chapter:2 @chapter:28


# Publication Year: -
# Title: Citrine from Zambia
# Abstract: Figure 1. These citrines (3.38–43.86 ct) showing the range of color from the new Zambian deposit are reportedly untreated. Photo by Robert Weldon.

                      In September 2011, GIA was informed by gem and mineral dealer Dudley Blauwet about a new find of citrine, which was represented to him as natural-color material from the Kitwe area of Zambia. He obtained ~1 kg of the rough at the 2011 Tucson gem shows from a regular supplier of African rough. Faceting of 208.5 grams of rough yielded 29 stones totaling 268.08 carats. Four of the stones were concave cut, and the largest one weighed 48.69 ct.

	Figure 2. Hazy clouds and bands are common features in the Zambian citrine. Photomicrograph by D. Beaton; image width 2.7 mm.
Mr. Blauwet loaned seven of the cut citrines to GIA for examination, ranging from 3.38 to 43.86 ct (figure 1). Concave facets on the three largest pieces accentuated their brilliance. The color of the citrine ranged from pale slightly brownish yellow to brownish orangy yellow, and the seven stones showed the following gemological properties: RI— no = 1.542, ne = 1.552; birefringence—0.010; hydrostatic SG—2.65–2.66; UV fluorescence—inert to both long- and short-wave UV radiation, except for one pale yellow sample that fluoresced very weak white to long-wave UV; and no features seen with the desk-model spectroscope. Microscopic examination revealed straight and angular color zones, as well as a general haziness and bands of hazy particles (figure 2), which proved natural origin and were similar to those described in citrine from Sri Lanka (E. J. Gübelin and J. I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 2, Opinio Publishers, Basel, Switzerland, 2005, p. 573). The 3.38 ct stone also contained a plane of parallel tubules and two-phase inclusions (figure 3). Viewed with cross-polarized light, minor areas of Brazil-law twinning were seen in only the two smallest samples.

	Figure 3. The 3.38 ct triangular modified brilliant in figure 7 contains a plane of elongated
	tubules and two-phase inclusions. Photomicrograph by D. Beaton; image width 1.5 mm.
FTIR spectroscopy revealed the absence of a 3595 cm–1 band. This feature is sometimes used as confirmation of natural quartz, especially amethyst, when it is well resolved and there are no diagnostic natural inclusions (S. Karampelas et al., “Infrared spectroscopy of natural vs. synthetic amethyst: An update,” Fall 2011 G&G, pp. 196–201). In citrine this feature is often absent, so proper identification must rely on inclusion observation, or the analysis of trace elements (C. M. Breeding, “Using LA-ICP-MS analysis for the separation of natural and synthetic amethyst and citrine,” www.gia.edu/gia-news-research-nr73109a).

Natural-color citrine is less common than other quartz varieties such as amethyst and smoky quartz. Assuming that the coloration of this citrine is natural—as represented by the supplier—this large, clean material makes a nice addition to the gem market. @chapter:0 @chapter:0 @chapter:0


# Publication Year: 2014
# Title: Challenges in Orienting Alexandrite: The Usambara and Other Optical Effects in Synthetic HOC-Grown Russian Alexandrite
# Abstract: K. Schmetzer, H.-J. Bernhardt, W. A. Balmer, and T. Hainschwang. “Synthetic alexandrites grown by the HOC method in Russia: Internal features related to the growth technique and colorimetric investigation,” Journal of Gemmology, Vol. 33, No. 5–6, 2013, pp. 113–129. Photo courtesy of Karl Schmetzer.

Dr. Schmetzer and his coauthors contribute another gemological description of a unique source of synthetic alexandrite, the chromium-bearing variety of chrysoberyl. These crystals, grown in Russia since the late 1980s and similar in color to natural alexandrites from the Hematita deposit in Minas Gerais, Brazil, were formed using a direct melt gradient technique. This alexandrite crystal growth process, developed by Dr. Vladimir Gurov, uses the horizontally oriented crystallization (HOC) method. The crystals have all been grown along the b-axis in molybdenum crucibles that contain both the melt and the solidified portion.

These crystals, which range up to 450 g, are used both for laser applications and gem-quality synthetics. Since 1994, they have been produced for the gem market in a joint venture with the Tairus company in Novosibirsk. Among their distinguishing inclusions are curved growth striae (similar to Czochralski-grown material and sometimes accompanied by bubbles), elongated and irregularly shaped flat cavities (figure 1), some rare occurrences of tiny birefringent crystals, and the occasional appearance of irregularly oriented fibers and fissures. Of note is the very uniform distribution of the chromophores Cr3+ and V3+ within the material. The amount of Fe3+ found in this material is extremely low.

Figure 1. The illustration demonstrates the three optical effects studied in the article: Pleochroism, the alexandrite effect, and the Usambara effect. Represented are two oriented cubes of HOC synthetic alexandrite with edge lengths of 3mm and 8mm viewed in unpolarized daylight and incandescent light down the a-, b- and c-axes. With identical lighting and edge length, pleochroism is clearly seen. The alexandrite effect is illustrated by comparing same size cubes along the same axis but under different lighting. Comparing the two different cubes under the same lighting and orientation, the Usambara effect is observed. Photos and artwork by Karl Schmetzer.
Of particular interest in this latest study of synthetic alexandrite, made possible by rare access to uniformly doped material, was the investigation of color related to various optical effects: the alexandrite effect (color change between daylight and incandescent light), the Usambara effect (variable coloration according to the path length of light), and pleochroism (coloration in views parallel to the three crystallographic axes). To accomplish this, the authors used a series of crystallographically oriented cubes with edges ranging from 2 to 10 mm. A particularly notable finding is that, similar to chromium-containing tourmaline, larger crystals display more redness (and less greenness) in all three directions of view. The Usambara effect, the variation of color with material thickness (assuming uniform lighting conditions), was first reported in 1997 (A. Halvorsen and B.B. Jensen, “A new colour-change effect,” Journal of Gemmology, Vol. 25, No. 5, pp. 325–330) and further described by Kurt Nassau in 2001 (The Physics and Chemistry of Color: The Fifteen Causes of Color, 2nd ed., Wiley, New York, pp. 94–96). Essentially, a material can have a variable transmittance in different areas, depending on the thickness of the material.

Additional color variations are described for the individual crystal orientations between daylight and incandescent light (figure 2). The subsequent discussion shows why it is difficult to ideally orient the table facet of an alexandrite with variable chromium concentrations and thicknesses. Also, there truly is no single orientation that maximizes the purest green and displays the most dramatic color change from daylight to incandescent light. This presents a formidable challenge to the gem cutter. Further research to investigate the impact of chromophore concentration (particularly Cr3+) on alexandrite’s color properties would be useful in fully describing this unique gem’s unusual range of appearances. @chapter:26 @chapter:0 @chapter:26


# Publication Year: 2019
# Title: Reinvesting in Cartagena: Jewelry School of the Caribbean
# Abstract: Alfredo Diaz (Caribe Jewelry, Cartagena, Colombia) spoke to the authors about the Jewelry School of the Caribbean (FEJOCAR), a nonprofit organization that teaches at-risk youth the art of jewelry making.
Working as a tour guide in his native Colombia, Diaz was frequently asked by tourists where to buy jewelry. He and his brothers opened a small jewelry repair workshop in 1983, catering to both tourists and locals. They expanded into selling their own small jewelry pieces, often featuring Colombian emerald. They sold through other businesses at first but eventually began selling pieces directly to the public. As they made more money, the brothers realized it was important to generate more employment in Cartagena. In 2009 they formed FEJOCAR and began outreach to poverty-stricken areas of the city, focusing on young people from neighborhoods with heavy gang and criminal activity.
The school accepts 75 students per year. Once enrolled, the students may choose between the jewelry design, manufacturing, gemstone polishing, and goldsmithing tracks. Caribe hires the most promising students for their own business. The education at FEJOCAR involves knowledge of jewelry techniques and training in software so that the students can use CAD/CAM and create prototypes. The gem polishing and jewelry design programs take four to six months to complete, while the jewelry manufacturing and goldsmithing tracks take one year.
The Diaz brothers faced challenges at the outset of the program. Some found it hard to believe that the brothers would trust their new employees, some of whom had criminal backgrounds. In fact, Diaz said, trust is essential to their working relationships. Employees appreciate this trust and respond in kind. While investigating student absences, they found out that many did not have the money for transportation or meals, so they started providing transportation fees and breakfast and lunch on-site. Today, FEJOCAR provides 30 full scholarships to help students in need enroll and complete their programs. Of the 120 employees at Caribe Jewelry’s stores, about 40 were recipients of scholarships.
About 60% of their students are women, a dramatic shift from when the program began; at the start, all of the goldsmithing students were men. Diaz also intends to set up home workshops for employees who are mothers, to reduce their need for childcare while maintaining production. They have plans for one employee to polish emeralds at home; the other will have a goldsmithing station.
Emeralds are very important to Colombia and to Caribe Jewelry; to that end, the Diazes have set up the Emerald Museum at their store on Bocagrande Calle in Cartagena. The highlight of the museum is “Petra,” the largest emerald in matrix ever to emerge from Colombia. They also have space dedicated to other varieties of beryl, including heliodor, aquamarine, red beryl, and goshenite.
The success of the school led the Diazes to move to a larger building to accommodate their students; they have also been able to increase their in-house production. Diaz said their long-term goal is to produce 90% of their own jewelry and buy 10% of their goods from wholesalers; at this point they produce 60% of their own pieces (up from last year’s 30%). One of the benefits of local craftsmanship is the ability to maintain a distinctive look that incorporates pre-Columbian indigenous imagery, separating it from Chinese or European designs. Another is the interaction between employees and tourists. The school offers a class for tourists wherein each visitor is paired with a FEJOCAR student. Visitors tour the museum before sitting down to make a piece of jewelry and getting to know a Cartagena local, a wonderful experience for both tourist and student. The Diaz brothers look forward to expanding their business, the school, and their students’ horizons in the years to come. @chapter:45 @chapter:2 @chapter:45


# Publication Year: 1962
# Title: Rapid Sight Estimates of Diamond Cutting Quality
# Abstract: A diamond brilliant’s beauty is the result of a complex combination of angles and proportions. In this article, Richard Liddicoat shows gemologists how to become familiar with how variations in cutting angles can affect a diamond’s face-up appearance. Using Marcel Tolkowsky’s ideal cut as a point of reference, Liddicoat presents techniques for estimating a particular diamond’s proportion values, describing how variables such as pavilion depth and size of table reflection influence the overall look and quality of a round brilliant. @chapter:41 @chapter:1 @chapter:41


# Publication Year: 1994
# Title: Synthetic Rubies by Douros: A New Challenge for Gemologists
# Abstract: Greek manufacturer J. & A. Douros introduced a new flux synthetic ruby in early 1993. Grown by spontaneous nucleation in a lead-based solvent, the Douros synthetic ruby occurs as rhombohedral single crystals and twinned tabular crystals, as well as in clusters. The tabular crystals typically have intense red cores that gradually decrease in saturation to a near-colorless outermost layer; the rhombohedra1 crystals have a deep red body and a thin near-colorless laver on the rhombohedral faces, with umbrella-like growth patterns in some areas. Some samples contain distinctive inclusions of yellow residual flux with spherical bubbles. Chemically, the crystals are heavily zoned, and EDXRF analyses revealed variable trace amounts of Ti, Fe, Cr, and Ga, as well as some Pb. SEMEDS identified the flux particles as lead bearing. Microprobe analyses showed high Cr values in the crystal cores; in certain growth zones, Fe replaces Cr in the outermost layers. If inclusions or typical growth structures are not present, chemical composition appears to be the best means of separating these Douros synthetic rubies from natural rubies. @chapter:19 @chapter:0 @chapter:19


# Publication Year: 2024
# Title: Rose Channels in Ruby
# Abstract: Rose channels in a 0.5 ct ruby. Photomicrograph by Aamir Sayed; field of view 0.75 mm.
The author recently examined a 0.5 ct pear-shaped ruby measuring 6 × 4 mm that contained twinning planes and hollow channels known as Rose channels (see above). Because the Rose channels were hollow and empty, they had a refractive index of 1 (the RI of air), while the RI of the surrounding host ruby was 1.76–1.77. The contrasting refractive indices resulted in high optical relief, making the Rose channels easily visible. These linear inclusions are common in natural corundum and were once thought to be boehmite needles (F. Notari et al., “‘Boehmite needles’ in corundum are Rose channels,” Fall 2018 G&G, p. 257). @chapter:19 @chapter:0 @chapter:19


# Publication Year: 2017
# Title: HPHT Synthetic Diamond Melee Without Si or Ni Defects
# Abstract: Figure 1. These four near-colorless round brilliant melee were identified as HPHT synthetic diamonds lacking the typical Si- and Ni-related defects. Photo by Nuttapol Kitdee.

	Near-colorless synthetic diamond melee grown using the high-pressure, high-temperature (HPHT) method have created significant concern in the industry, and various screening methods have been developed to take into account their most reliable distinguishing features. In general, the specimens described in previous Lab Notes (e.g. Summer 2015, pp. 183–184) were very small round faceted goods ranging between 0.005 and 0.01 ct.

	Recently GIA’s Bangkok laboratory received four loose near-colorless round brilliants for quality assurance service (figure 1). They weighed between 0.07 and 0.09 ct, slightly more than previously submitted melee. All were identified as type IIb HPHT-grown material using Fourier-transform infrared (FTIR) spectroscopy. Their most interesting feature was the absence of silicon- or nickel-related emission peaks when analyzed at liquid nitrogen temperature by photoluminescence (PL) spectroscopy (figure 2). The spectra typically observed in HPHT synthetic diamonds show an emission doublet related to the negatively charged silicon split-vacancy defect SiVˉ at 736.6/736.9 nm and an associated Ni-related defect at 883.0/884.7 nm.

	Figure 2. The PL spectra features observed at liquid nitrogen temperature lacked the 736.6/736.9 nm emission doublet related to the SiV– defect (left, 514 laser excitation) and the Ni-related defect doublet at 883/884 nm (right, 830 nm laser excitation).

	The growth patterns observed in the DiamondView were an identifying feature that did remain the same. The characteristic angular growth patterns and blue-green fluorescence, together with an associated green phosphorescence, still provide important evidence that aid in the separation of natural and synthetic diamonds (figure 3). Examination with a gemological microscope revealed metallic and rod-like inclusions (figure 4) that also assisted in identifying these melee as synthetic diamonds.

	Figure 3. These DiamondView fluorescence and phosphorescence images of a 0.081 ct sample show growth patterns characteristic of HPHT synthetic diamond. Image by Charuwong Khowpong.

	Figure 4. Darkfield illumination reveals rod-like inclusions in a 0.087 ct HPHT-grown melee diamond. Photomicrograph by Charuwan Khowpong and Ungkhana Atikarnsakul.

	The study of these four melee-size HPHT synthetic diamonds revealed atypical PL spectra. However, other means of identification (inclusions, growth patterns as seen via the DiamondView, and their phosphorescence reactions) still played an important role in their identification. It is interesting to note that HPHT synthetic melee diamonds being submitted to GIA for identification are getting larger, indicating the continuous improvement of synthetic technology. @chapter:9 @chapter:1 @chapter:9


# Publication Year: -
# Title: An Update on Sapphires with Unstable Color
# Abstract: Figure 1. A padparadscha sapphire (3.54 ct) submitted to the GIA laboratory increased its orange color during the color stability test. If left in the dark for an extended period of time, the color could become less orange or even go to straight pink. This can be replicated by exposing the sapphire to intense LED illumination. This stone would be characterized as a padparadscha sapphire because the pink-orange color after the stability test is acceptable. Photos by Diego Sanchez.
GIA has been performing color stability testing on some sapphires for decades (Crowningshield, 1969). More recently, the stability test has been implemented to identify pink sapphires that can be charged with UV light to create a temporary change of color into the orangy pink to pinkish orange range of padparadscha sapphires or even more orange in appearance. A few hours of exposure to intense incandescent illumination will cause the unstable orange component to fade away, returning the stone to a pink appearance. A sapphire will only be characterized as a padparadscha if the color is acceptable after this stability test. Temporary, unstable orangy pink to pinkish orange coloration does not qualify for the padparadscha characterization if the stone shows coloration outside of this range after the stability test. This change will also occur upon exposure to sunlight, although it takes longer. The color stability test and observations above are described in some detail by Nassau and Valente (1987), Krzemnicki et al. (2018), Smith et al. (2019), Hughes (2022), Wang et al. (2022), and Tsai et al. (2022).
However, GIA has observed that some sapphires react to the color stability test by gaining orange or yellow coloration upon exposure to incandescent light (figure 1). Some pink sapphires might shift to a padparadscha color or even to pure orange, and the saturation of pale yellow sapphires can increase (figure 2).

Figure 2. Any color-unstable sapphire will exhibit the behavior of gaining yellow or orange color during the stability test if starting from the ground state, such as this yellow sapphire (0.64 ct) and padparadscha sapphire (0.89 ct). The color produced from charging with a UV light is also shown. Photos by Diego Sanchez (top row) and Adriana Gudino (bottom row).
This orange intensifying reaction is due to the small component of UV light present in the incandescent light used. The UV component creates unstable color centers at the same time they are being destroyed by visible wavelengths of light. If one of these sapphires is stored in a dark place for an extended period, it will fade to the ground state, typically purplish pink, pink, or pale yellow. This ground state can also be achieved by heating (>150°–300°C) or exposure to intense white LED light with no UV component. Subsequent exposure to any light source containing UV—including sunlight—will again show the orange or yellow color (figure 3). This behavior of gaining color during the stability test has been observed in all color-unstable sapphires used in this research project after fading to their ground state under intense LED illumination or when left in the dark. While this is not part of GIA’s normal testing procedures for color-unstable sapphires, it is expected that any color-unstable sapphire could behave similarly and gain color during the stability test to some extent, depending on its initial color (e.g., if left in the dark for extended time). Further, color instability may not always be identified by the stability test if the initial color is close to that produced by exposure to incandescent light. The property of changing color with exposure to UV is referred to as tenebrescence, or reverse photochromism. Tenebrescent stones are known to fade back to their original color when exposed to sunlight.

Figure 3. For this color-unstable beryllium-diffused sapphire (1.94 ct), the stability test produced a color similar to that seen after exposure to intense sunlight. A similar effect was observed when the sapphire was set in a simple ring and worn by author AP’s wife for five days. While the color after the stability test might have been acceptable for padparadscha, this characterization does not apply to beryllium-diffused sapphires. Photos by Diego Sanchez and Adriana Gudino (bottom right).
These observations raise an important question about how gemological laboratories should determine the color of tenebrescent sapphires, and which color should be used to describe the stone. In GIA’s experiments, the color observed after the color stability test is very similar to what was observed after exposure to daylight, which would be expected if set in jewelry and worn frequently. Given this, and given the need for a consistent and easily accessible standard, the color after the incandescent light stability test is the color indicated by GIA on colored stone reports for these sapphires. This is the case regardless of whether a sapphire loses or gains yellow/orange color during the test. Full results of GIA’s research into this important matter are currently being prepared for publication in Gems & Gemology in the near future. @chapter:19 @chapter:1 @chapter:19


# Publication Year: 2009
# Title: Identification of the Endangered Pink-To-Red Stylaster Corals by Raman Spectroscopy
# Abstract: All corals within the Stylasteridae family (including the Stylaster genus) are listed in Appendix II of CITES; this means they are protected and their trade requires an export permit, unlike corals from the Corallium genus, which include most pink-to-red corals used in jewelry. Raman scattering demonstrates that corals from the Stylaster genus contain carotenoid pigments (polyenic pigments substituted with methyl groups), whereas those from the Corallium genus are colored by unmethylated polyenic pigments. Additionally, Stylaster corals are made of aragonite, whereas those from Corallium are composed of calcite. Through Raman scattering analysis, the fully protected Stylaster pink-to-red corals may be distinguished from this other type of gem coral. @chapter:54 @chapter:4 @chapter:54