# Publication Year: 2014
# Title: Challenges and Opportunities
# Abstract: Welcome to the second issue of our 80th year!

In June, GIA held a reception at our Carlsbad headquarters to celebrate this anniversary and to honor the artistry of Harold and Erica Van Pelt. The reception marked the opening of a museum exhibition of their G&G cover shots, displayed alongside many of the fabulous pieces they photographed. The Van Pelts’ beautiful images graced the covers of our journal for nearly 30 years, and really symbolized the stature and quality of G&G.

Along with GIA president Susan Jacques, editor-in-chief emeritus Alice Keller, and frequent contributor John King, I was privileged to offer a few words to our guests. While the others spoke to G&G’s context, its place at the heart of GIA’s mission, and the contributions that enriched the journal over the years, my topic was the future. Although there are undoubtedly challenges in living up to G&G’s 80-year legacy, there are corresponding opportunities to take our journal to a much wider audience. While technology and social media provide much of this new potential, it’s also abundantly clear how well people respond to the printed journal, and how important face-to-face contact is for transforming ideas into reality. As we plan for the future, our strategy needs to incorporate both elements.

Our lead article in the summer issue, by GIA’s Robert Weldon and Russell Shor, examines the progress Botswana has made toward becoming a major diamond processing and jewelry manufacturing center. The country has a history—primarily through the rich diamond mines in its territories—of harnessing natural resources for the benefit of its people. The authors examine the current status of Botswana’s cutting industry and its prospects for the future. The article draws from Weldon’s 2013 visit to Botswana with GIA videographer Kevin Schumacher, whose extensive videos illuminate many of the locations and people described in the paper.

In the minds of many practicing gemologists, three-phase inclusions in emerald are inextricably linked to Colombian origin. Yet emeralds from Afghan, Chinese, and Zambian deposits can display strikingly similar multiphase inclusions. Sudarat Saeseaw, Supharart Sangsawong, and Vincent Pardieu, all from GIA’s Bangkok laboratory, present detailed photomicrographs of samples from these localities and combine this study with spectroscopy and trace-element analysis. The authors demonstrate that the combination of these techniques has significant potential for the geographic origin determination of emerald.

We also offer a fascinating paper examining the blue color phenomena seen in some Dominican and Indonesian amber. Yan Liu of Liu Research Laboratories and coauthors Guanghai Shi and Shen Wang provide the gemological basis for the surface-related blue fluorescence seen in such amber.

Our final feature article—also on amber—comes from Yamei Wang and Mingxing Yang, both of the China University of Geosciences in Wuhan, and Yiping Yang, a former postgraduate from the same institution. This paper documents their heat treatment experiments on a range of amber samples, which successfully reproduced some of the products found in today’s jewelry marketplace. Along with the methods and results of their experiments, the authors present criteria for identifying heated amber.

In addition to these feature articles, you’ll find a variety of updates in our regular Lab Notes and Gem News International sections.

One of our continuing priorities is to develop synergy with the GIA website. In this issue, we entreat you to visit—in case you missed them—our recent article posts and related videos. You’ll hear the voices of researchers, miners, and gem professionals, and see inside research institutions, mines, museums, and the diverse locations where gems are bought and sold.

We hope you enjoy the summer 2014 edition! @chapter:38 @chapter:3 @chapter:38


# Publication Year: -
# Title: Bargaining for Gems in Chanthaburi
# Abstract: Buyers await sales offers at the teeming Chanthaburi gem market, held every weekend. Many buyers post handwritten signs detailing their wants at the front of the table or on the walls behind them.

                      A middle-aged woman in a floral dress and sun visor zips open a plastic bag and spreads an array of polished rubies across a desk blotter, taking care to keep them in the sunlight, where the colors come through richer. Behind the desk, a bushy-bearded buyer combs through the parcel with his tweezers, setting aside a dozen stones in about as many seconds. The dealer punches a per-carat price into her calculator. The buyer types in a counteroffer, and the two silently bargain until a deal is struck.

At the Chanthaburi gem market in southeastern Thailand, where buyer and seller often speak no common language, the calculator is a universal translator.

	Buyers sort through a prospective parcel of polished ruby at the Chanthaburi market while the runner awaits their offers. For buyers who don’t speak Thai, the calculator serves as the universal translator.
Chanthaburi’s gem trade dates back centuries—accounts of mining and trading there began in the 15th century—and today its gem market remains one of the world’s largest and liveliest.

Thailand is one of the world’s leading colored gemstone cutting and trading centers. It exported an estimated $650 million worth of gemstones during 2012—about half of that sapphire, according to the Gem and Jewelry Institute of Thailand. While most traders keep their export offices in Bangkok, the traditional center of the colored stone industry, the place where nearly all of the cutting is done, is Chanthaburi. This town of about 30,000 lies 150 miles southeast of Bangkok, near the old ruby and sapphire mining area of Pailin on the Cambodian border.

	A buyer checks a large parcel of blue sapphire in the open-air Chanthaburi market while the dealer holds the rest of the lot.
The Chanthaburi gem market is a relatively quiet place during the week, with a few dozen dealer shops on narrow Si Chan Road offering loose gemstones, gold settings, and equipment, such as electronic scales, lighting, and loupes and tweezers. But the weekend is when the market truly comes alive, spilling into the neighboring streets and alleys. Beginning at 10 am Friday, hundreds of dealers from around the country and many parts of the world set up makeshift stands with scales, calculators and, of course, gems. Within 30 minutes, the streets are teeming with buyers, brokers, sellers and an occasional tourist. The trading continues until dusk. Unlike traditional markets, most of the people sitting at the tables and desks are buyers, not sellers.

	Some of the buildings along Si Chan Road are weekend stone exchanges where buyers and sellers don’t have to worry about the sudden downpours that can arrive at any time during the spring and fall.
The center of the action is at the intersection of Si Chan Road and Thetsaban Road, where the streets serve as an impromptu gem exchange. Buyers will find a seat at a table, sometimes posting a sign listing their wants, and wait for brokers or dealers. Runners working with the dealers dash from table to table, taking orders, showing gems and carrying price offers back to their bosses. Some dealers hurry to intercept the buyers before they get to the tables so they don’t have to pay commission to the table owners.

What’s for sale? Not surprisingly, a vast majority of the dealers were offering ruby and sapphire of all colors—some for as little as $2 or $3 per carat. Are treatments disclosed? The price is the disclosure, said one dealer who’d stopped by to show a parcel of ruby. Sellers also showed spinel, various colors of tourmaline, tsavorite and spessartite garnet, and even amethyst and citrine. Between the gem vendors and exchanges is a veritable smorgasbord of street food, with vendors offering noodles, barbecue chicken, mangoes and soup bowls.

	Si Chan Road leads to the gem market in Chanthaburi—the street lamps pay tribute to the main commerce in this city of 30,000 inhabitants.
On the side streets behind the market are dozens of “burners,” operations that apply heat and other treatments to gemstones. Most of these have no sign out front but are well known to the local trade.

Veteran dealers say the trading at the market is quieter than a decade ago. They blame Western governments’ sanctions on Myanmar and the general economic malaise in many key consuming markets. But the market has survived transitions before. Indeed, Chanthaburi’s gem trade has been rejuvenated to some degree by diffusion treatments that can turn unattractive (and unsellable) corundum into low-cost yellow sapphire. Because of this, at least 10 mine sites are now in operation near Khao Ploy Waen and Ban Ka Cha. Additionally, one site produces black star sapphire that is not treated.

	The Chanthaburi province was once a prolific producer of ruby and sapphire. This mine, about 10 miles from the city, is a source of yellow sapphire.
Despite the slower sales, dealers such as the woman in the floral dress believe Chanthaburi will always have a place in the world gem business, because the skills and the infrastructure vital to the industry are still concentrated here. @chapter:38 @chapter:2 @chapter:38


# Publication Year: 1998
# Title: Winter 1998 G&G Book Reviews
# Abstract: “Bulgari”
By Daniela Mascetti and Amanda Triossi, 225 pp., illus., publ. by Abbeville Press, New York, NY, 1996. US$75.00

“Collecting and Classifying Colored Diamonds: An Illustrated Study of the Aurora Collection”
By Stephen C. Hofer, 742 pp., illus., publ. by Ashland Press, New York, NY, 1998. US$300.00

“The Nature of Diamonds”
Edited by George E. Harlow, 278 pp., illus., publ. by Cambridge University Press, New York, NY, 1998. US$29.95 (softbound)

“Glossary of Geology, 4th Edition”
Edited by Julia A. Jackson, 769 pp., publ. by the American Geological Institute, Alexandria, VA, 1997. US$110.00

“Gem and Jewellry Year Book 1997–98”
Edited by V. V. Kala and A. Kala, 697 pp., illus., publ. by International Journal House, Jaipur, India [diaworld@jpl.vsnl.net.in], 1998. US$35.00 (surface), US$50.00 (air)

To view the full section, download the PDF above. @chapter:21 @chapter:1 @chapter:21


# Publication Year: 2016
# Title: Ruby and Sapphire from Muling, China
# Abstract: Figure 1. Muling, the site of an emerging corundum deposit, is located in northeastern China.

	Only a few Chinese sources produce gem-quality corundum, such as Changle, in Shandong province, but sapphires from that location are not considered top quality in the trade because of their dark hues. An emerging deposit in Muling, in northeast Heilongjiang province (figure 1), produces gem-quality corundum comparable to some world-renowned sources. The main deposits are seated in mountain valleys about 70 km from the town center. Corundum was known in Muling as early as 1985; after preliminary exploration, further activity virtually stopped because of technical and logistical limitations. As a result, production has been very limited, and very little information was published about rubies and sapphires from Muling until 1995 (J.X. Sun, “Basalt related to ruby and sapphire in eastern Heilongjiang and reconstruction of paleovolcanic mechanism,” Acta Petrologica et Mineralogica, Vol. 14, No. 2, 1995, pp. 126–132).

	According to Aijun Yi, director of mineral resource administration in Muling, the region has produced large amounts of gem-quality eluvial materials since 1994, including corundum, brownish red zircon, garnet, and spinel (T. Chen et al., “Brownish red zircon from Muling, China,” Spring 2011 G&G, pp. 36–41). As colored stones became more popular in the Chinese gem markets, interest in ruby and sapphire from Muling grew accordingly.

	We acquired a parcel of rubies and sapphires from local miners. The stones ranged from 0.8 to 15.2 ct (figure 2). Most exhibited well-formed tabular hexagonal crystals, though some broken sapphires had a tumbled appearance. The sapphires were pink, yellow, violetish blue, greenish blue, light blue, and deep blue; there were also near-colorless specimens. Most of the rubies and pink sapphires had a purplish component. Samples other than the deep blue material showed high transparency. Rubies and pink sapphires exhibited medium red fluorescence under long-wave (356 nm) UV light and a weak reaction under short-wave (245 nm) UV. Other varieties of sapphire had no reaction under long- or short-wave UV.

Figure 2. Ruby and sapphire rough from Muling exhibited well-formed tabular hexagonal crystal forms; some sapphires showed a tumbled appearance in broken pieces. Photo by Yimiao Liu.

	The samples generally showed abraded features and unhealed fissures, but some were predominantly clean under the loupe and large enough to be faceted. Fourteen stones were fabricated as parallel polished windows for microscopic examination. Several interesting internal features were visible under the microscope. The inclusions, which mainly appeared as rounded single crystals or multiphase syngenetic clusters, were in micron sizes (50–200 µm) and were identified by Raman as feldspar and sillimanite. The latter mineral only occurred as component mineral crystals in a multiphase inclusion. Most rubies hosted whitish needles forming three-dimensional skeleton networks that might be the result of diaspore exsolution (figure 3). Further microscopic observations under polarized light showed characteristic lamellar twining structures in every sample.

Figure 3. A detailed structure of whitish needles forming a three-dimensional skeleton network in a ruby sample. Photo by Yimiao Liu.

	Trace element analysis by LA-ICP-MS showed a Cr content of 173–636 ppma in the pink-red series, accompanied by a significant level of Fe (1650–2510 ppma) and a noticeable level of Ti (36–70 ppma) to add a blue component through Fe-Ti intervalence charge transfer. This explained why Muling rubies and pink sapphires always had a purplish hue. Mg content was about 46–79 ppma, while Ga (13–17 ppma) fell into the expected range for natural corundum.

	Yellow sapphires showed the highest Fe content (4480–4800 ppma); this contributed to their saturated yellow coloration. Iron content was much lower in blue sapphires, along with an appreciable amount of titanium (80–500 ppma) as a blue chromophore. Based on color distribution and transparency, blue sapphires could be grouped as either light blue or deep blue. Most of the light blue sapphires had very high transparency and even color distribution, while deep blue sapphires were less transparent, with hexagonal dark blue color zoning. Among all blue samples, Mg content ranged from 10 to 80 ppma and did not show clear correlation to color, while Ga content (10 to 100 ppma) was noticeably higher than in rubies and pink sapphires.

	At Muling, most rubies and sapphires are found by casual surface digging. Gem-quality corundum usually occurs in eluvial deposits derived from weathered Cenozoic alkali basalts. Unlike other igneous-related deposits known for dark blue sapphires and very limited red material, such as Australia’s Anakie and New England fields (T. Coldham, “Sapphires from Australia,” Fall 1985 G&G, pp. 130–146) and Shandong, China (C. Simonet. et al., “A classification of gem corundum deposits aimed towards gem exploration,” Ore Geology Reviews, Vol. 34, 2008, pp. 127–133), in Muling ruby production was larger than that of sapphire; over 60% of pink sapphires and rubies were high-quality materials.

	In some ways, some Muling rubies have competitive advantages over Mozambique specimens. Their high color saturations and particular internal features (whitish needles forming three-dimensional skeleton networks) resembled those of rubies from Mozambique and might cause confusion in gem markets. On the other hand, blue sapphires from Muling have a pure blue color with no gray component. The variety of colors and the amount of fancy sapphires found in Muling are quite different from sapphires from other classic igneous deposits (see again Simonet et al., 2008).

	At present, the precise location of the Muling gem deposit source rocks has not been confirmed. According to previous geological studies, the area is localized in the northern terminal of the branch of the Tanlu fault (Z. L. Qiu et al., “Trace element and hafnium isotopes of Cenozoic basalt-related zircon megacrysts at Muling, Heilongjiang Province, northeast China,” Acta Petrologica Sinica, Vol. 23, No. 2, 2007, pp. 481–492). The lava in this region can be divided into six volcanic eruption cycles; Muling has experienced three such cycles (Sun et al., 2005).

	Based on mining and geological information and our analysis of Muling rubies and sapphires, we inferred that this material might have originated as xenocrysts from an earlier volcanic eruption and undergone subsequent high-pressure geological processes. These are likely non-classic alkali basalt deposits. Large corundum deposits exist from eastern China to Primorye in far eastern Russia (I. Graham et al., “Advances in our understanding of the gem corundum deposits of the West Pacific continental margins intraplate basaltic fields,” Ore Geology Reviews, Vol. 34, pp. 200–215), but exact locations have not been confirmed.

	Although Muling’s corundum deposit have yet to be mined commercially, the existing production has drawn the attention of Chinese gemologists and gem dealers. The production may rival that from other high-quality deposits, and this source holds great promise for the future. @chapter:0 @chapter:0 @chapter:0


# Publication Year: 2016
# Title: Treated Pink Type IIa Diamond Colored by Red Luminescence
# Abstract: Figure 1. This 4.29 ct type IIa color-treated diamond was graded as Fancy brown-pink under daylight conditions (left) and appeared Fancy purplish gray under incandescent lighting (right). The color change is due to strong NV fluorescence under UV to blue light exposure and irradiation-related GR1 absorption under incandescent illumination. Photo by Robison McMurtry.
Recently, the Carlsbad laboratory received a 4.29 ct type IIa diamond for color origin determination. In daylight-equivalent illumination, the diamond was color graded as Fancy brown-pink, but under incandescent light it appeared Fancy purplish gray (figure 1).

When exposed to long-wave UV light at 365 nm, the diamond exhibited medium orange fluorescence. Based on photoluminescence (PL) spectroscopy, collected using several lasers, it was identified as a treated diamond that had been subjected to high-pressure, high-temperature (HPHT) annealing, irradiation, and subsequent low-pressure annealing. The PL spectra were dominated by the presence of strong NV centers at 575 and 637 nm, along with a strong GR1 peak, confirming the cause of the diamond’s luminescence as the NV centers.

UV-Vis-NIR absorption spectra were collected at room temperature (figure 2) and at liquid nitrogen temperature inside an integrating sphere for this diamond (along with a 0.48 ct treated pink CVD synthetic that does not show the pronounced color change, for comparison). At liquid nitrogen temperature with the diamond under incandescent illumination, the most prominent feature was the GR1 peak creating the purplish gray coloration, comparable to the blue color generated in many irradiated type IIa diamonds. In daylight-equivalent illumination, the emissions of the NV0 and NV– centers were superimposed on the absorption spectrum, thus influencing the diamond’s color within the yellow to red region of the visible spectrum. Color grading of diamonds includes the effect of fluorescence, and therefore the reported color was Fancy brown-pink.

Figure 2. Room-temperature UV-Vis-NIR absorption spectra were collected on the
4.29 ct treated sample (red trace) and a 0.48 ct treated CVD synthetic (blue trace) with
a color grade of Fancy Vivid purplish pink. While NV-related red luminescence caused
a pronounced difference in color for the 4.29 ct sample, it only produced a minor change
in the treated CVD synthetic. In incandescent light (and with minimal influence of the red
luminescence), the synthetic’s color shifted slightly to Fancy Deep purplish pink. The
pronounced absorption from the GR1 peak (550–750 nm) within the 4.29 ct diamond
accounts for the purplish gray color in incandescent lighting.
While treated diamonds have pronounced UV fluorescence due to NV centers, fluorescence spectra collected at a variety of wavelengths show that the NV luminescence is actually stronger when excitation is from blue light (450–500 nm) than from ultraviolet wavelengths, as in the case of this stone (figure 3). This strong emission stimulated by visible light indicates the diamond is colored by red luminescence in response to blue light and, to a lesser extent, by fluorescence due to the UV component in daylight. Other treated pink diamonds, colored by NV absorption, showed similar excitation spectra (Y. Luo and C.M. Breeding, “Fluorescence produced by optical defects in diamond,” Summer 2013 G&G, pp. 82–97). This red luminescence due to NV centers is comparable to the more commonly noted green transmission luminescence from the H3 centers seen in some yellow diamonds. Such yellow diamonds receive greenish color grades due to the visible influence of the green emission on the perceived color in daylight conditions.

Figure 3. These 3-D fluorescence spectra were collected using excitation from the UV
range through the blue range of visible light (320–520 nm). The corresponding
fluorescence spectra show that the relative intensity is much higher when excited by
wavelengths within the visible region than in the UV region. This indicates that red
luminescence excited by visible light is a greater contributor to the pink color than the
UV-activated fluorescence. The 0.48 ct treated CVD synthetic shown in figure 2
demonstrated identical behavior—refer to Luo and Breeding (2016) for comparable
spectra—and indicates that NV-related luminescence contributes to the graded color
in many pink diamonds that are colored by NV centers. The excitation artifact occurs
when the emission spectrometer scans across the excitation wavelength.
For most treated pink diamonds, red luminescence corresponds with and enhances the pink bodycolor (Fall 2011 Lab Notes, pp. 228–229), much like chromium-related red fluorescence enhances the color of rubies. Since bodycolor closely corresponds to luminescence color for most treated pink diamonds, the color difference between daylight and incandescent light sources is minimal. For example, the 0.48 ct treated pink CVD synthetic diamond (figure 2, blue trace) was color graded as Fancy Vivid purplish pink using a daylight-equivalent light and as Fancy Deep purplish pink under an incandescent light. The NV-related emission, excited by the UV to blue light, brightened the diamond in that viewing environment.

The purplish gray bodycolor for this 4.29 ct treated diamond seen under incandescent light derived from the strong GR1 absorption induced by irradiation. The GR1 intensity, as measured by 633 nm photoluminescence spectroscopy and normalized using the diamond Raman peak, was compared with 20 other treated pink diamonds that did not show a substantial color shift. The GR1 intensity of this diamond was 8 times greater than the average value of the 20 treated pink diamonds and 3.5 times greater than the highest value. The GR1 intensity of this diamond was comparable to irradiated green to blue diamonds. In incandescent light, the red luminescence appeared to provide a minimal contribution, as the modifying hue was purplish (implying a reddish component) and not bluish as one might reasonably expect for an irradiated diamond.

Other diamonds have shown a shift in color grade due to appreciable fluorescence. Examples include the 56.07 ct Tavernier diamond, which displays a brown to pink color shift (Y. Liu et al., “The alexandrite effect of the Tavernier diamond caused by fluorescence,” Color Research and Application, Vol. 23, No. 5, 1998, pp. 323–327), and a few type Ib diamonds with a NV-related color shift from greenish brown to orangy brown (Fall 2011 GNI, pp. 234–235).

Some CVD-grown diamonds also have shown a pink to blue color shift, but due to an entirely different mechanism. In those synthetic diamonds, the color change was caused not by a difference in light sources, but by a temporary charge-transfer effect activated by UV exposure. For those CVD synthetics with a high concentration of silicon impurities, UV exposure precipitated a charge transfer between negative and neutral silicon-vacancy centers. In one CVD specimen, the relative concentrations of SiV– and SiV0 were essentially reversed with UV exposure and thus influenced the color change from its stable color of Fancy brown-pink to a temporary Fancy Intense blue (U. D’Haenens-Johansson et al., “CVD synthetic gem diamonds with high silicon-vacancy concentrations,” Conference on New Diamond and Nano Carbons, May 2015, Shizuoka, Japan).

The 4.29 ct natural diamond noted here was HPHT annealed and irradiated to create the NV centers. It appeared to have been irradiated to a far greater extent than most treated pink diamonds, and as a result it had a significantly higher GR1 intensity (as shown in figure 2 and confirmed with 633 nm PL). This accounts for its purplish gray color in incandescent light. The color change between these two attractive colors, along with its large size, makes this diamond quite unusual and serves to illustrate that the color of treated pink diamonds is assisted by red luminescence. This stone also demonstrates that while multiple treatments can provide for some identification challenges, they can also create some truly intriguing products. @chapter:22 @chapter:1 @chapter:22


# Publication Year: 2001
# Title: Hydrothermal Synthetic Red Beryl from the Institute of Crystallography, Moscow
# Abstract: Hydrothermal synthetic red beryl has been produced for jewelry applications by the Institute of Crystallography and an affiliated company, Emcom Ltd., both in Moscow. Diagnostic identification features include: a tabular crystal morphology, chevron-like and subparallel or slightly wavy internal growth zoning, sharp absorption bands at approximately 530, 545, 560, 570, and 590 nm due to Co2+, water-related absorption bands between 4200 and 3200 cm-1 in the infrared spectrum, and the presence of Co and Ni peaks in EDXRF spectra. @chapter:10 @chapter:0 @chapter:10


# Publication Year: 1983
# Title: Kashmir Sapphire
# Abstract: The unique beauty of gem sapphires from Kashmir has brought fame to a locality about which little has been reported in recent years. After an initial burst of activity 100 years ago, the production of these gemstones has slowed to a trickle and the majority of the corundum from these mines today is of industrial grade. Despite evidence of other gem mineral occurrences in the area, difficult terrain and political factors have impeded their exploitation. This article, the result of an expedition to the deposits in 1981, chronicles the history of the Kashmir mines, describes the characteristics of the sapphires found there, and examines the outlook for the future of this area. @chapter:30 @chapter:0 @chapter:30


# Publication Year: 1986
# Title: Fall 1986 Gem News International
# Abstract: Colored Stones
            Green-Fluorescing Emerald from Coscuez
            New Source of Gem Garnets from Idaho
            Blue Pectolite: Trade Name “Larimar”
            Fake Phosphorescent Quartz
            Color Change in Blue Zircon
Synthetics
            Gem-Quality Diamond Crystals
Announcements
            FIT Show in New York
            Iberjoya in Madrid
            Vicenzaoro 1 in Vicenza
            Jewelers International Showcase in Miami Beach
            BIJORHCA in Paris
            Tucson 1987
            INHORGENTA 87 in Munich
            International Fair in Sydney
            Platinum Jewellery Fair in Osaka

To view the full section, download the PDF above. @chapter:21 @chapter:0 @chapter:21


# Publication Year: -
# Title: Laboratory-Grown Diamonds: Demand Rises, Prices Fall
# Abstract: This 5.19 ct near-colorless type IIa CVD synthetic diamond is one of the largest faceted CVD synthetics seen at GIA. GIA photo

The proliferation of laboratory-grown diamonds into the market continues to dominate industry news.
A new report says demand for lab-grown diamonds has experienced “significant growth” from attractive marketing, but that prices for such goods have declined 70% in the past two years. The report, compiled by Bain & Co. and published by Rapaport, says the price decline is caused by improving technology that lowered production costs.
The consulting firm also noted that its consumer survey found that demand for lab-grown diamonds falls off sharply when their price tops $1,000 per carat.
Lab-grown producers, other than De Beers/Lightbox, claimed in the report that demand is running above supplies for their products, so prices are not dropping – especially for larger stones that remain difficult to produce.
The Bain view, however, is that prices will likely continue to decline to the point where the two markets “separate themselves,” similar to what happened with colored stones.
NATURAL DIAMONDS
The world’s two largest diamond miners – De Beers and Alrosa – continued cautious supply policies into the first third of the year. Both cut back on rough sales compared to last year, as their clients – diamond manufacturers – complain of softening prices and rising inventories, especially of small, lower quality goods.
The De Beers February/March cycle totaled $490 million, a 13% decline from the same period last year, but the firm held the line on prices after lowering them on some goods last fall. The trade generally welcomed the lower allocations, which include sight sales and individual deals, but claimed that softening polished prices have cut margins.
De Beers production also slid about 10% in 2018 – 32 million cts compared to 35 million cts in 2017 – although revenues increased 4% as the company shifted more of its sales toward higher quality goods.
De Beers noted: “The outlook for 2019 global diamond jewelry consumer demand faces a number of headwinds, including the risk of a potential intensification of U.S.-China trade tensions, the Chinese government’s ability to rebalance economic growth towards consumption, and further exchange rate volatility,”
Alrosa announced that its February rough sales were $340.6 million, up 23% over its January allocation. While the headline stated it was an increase, sales for the first two months of the year were more than 35% below the same period of 2017. The company did note improving demand from some Indian manufacturers, despite “some challenges hampering access to bank financing for the industry.”
KIMBERLEY PROCESS
The United Nations (U.N.) approved a resolution aimed at expanding the mandate of the Kimberley Process (K.P.) to exclude diamonds produced in a climate of “systemic violence” in addition to civil conflicts. This means that diamonds produced in areas where workers and local residents are killed, injured or abused by government, local militia or private security forces may be sanctioned if the measure is adopted. This is a major expansion that can allow, for the first time, diamonds from countries not engaged in civil wars to be excluded by the K.P.
Although the U.N. adopted the resolution and the World Diamond Council approved it, it’s hardly a done deal. The K.P. itself has to adopt the change, and, since that requires unanimous approval from every member country, nothing is guaranteed.
The U.S. tried to push this expansion a decade ago to no avail – it was met with fierce opposition from many African producer countries, particularly those bordering Zimbabwe, who feared reprisals from their larger neighbor. At that time, Zimbabwe’s government was under fire for major human rights abuses at the Marange mining area and assumed (not entirely wrongly) the change in the K.P. was directed at them.
After the U.N. approved the resolution, a coalition of non-governmental organizations (NGOs), The Civil Society Coalition, issued a call to ban diamonds from Zimbabwe based on the fact that the country’s army is involved the mining process. The army violently assumed control of the diamond deposits in 2006 after hundreds of artisanal miners had settled into the area to dig for stones. An estimated 180 people died in the conflict, while human rights abuses allegedly continued for years afterward.
An effort to expel Zimbabwe from the K.P. a decade ago was defeated on the grounds that Zimbabwe’s government was the recognized authority and that sanctions were only applied to rebel groups. @chapter:49 @chapter:3 @chapter:49


# Publication Year: -
# Title: 2017 Auction Roundup: Pink and Blue Fancy Colored Diamonds Still Rule
# Abstract: When it sold for $71 million at Sotheby’s Hong Kong in April, the GIA-graded 59.6 ct. Chow Tai Fook Pink Star became the most expensive gemstone ever sold at auction. Photo courtesy of Sotheby’s

More than $1.1 billion worth of extreme top-end diamonds, colored gems and jewelry were sold at auction by the world’s most renowned houses in 2017. While sales results at the two main auction houses, Christie’s and Sotheby’s, were strong, buyers were discerning, especially in the second half of the year when a number of important lots went unsold.

Christie’s sold $556.7 million worth of jewelry worldwide, $8.9 million in online auctions. Sotheby’s did not formally announce its yearly jewelry sales, but a tally of sales from the company's website totaled about $552 million.

The biggest news was the April 4 sale of the Pink Star diamond by Sotheby’s Hong Kong, which set a world price record for a gemstone at auction. The 59.60 ct Fancy Vivid pink Internally Flawless stone was the largest diamond of those grades ever graded by GIA and achieved the record price of $71.2 million. The buyer was Chow Tai Fook, the large Hong Kong-based retail jewelry chain.

The 24.78 carat, Fancy Intense pink, Graff Pink diamond sold in 2010 for more than $1.8 million per carat, which was more than the price per carat sale of the Pink Star in 2017. Photo courtesy of Sotheby's.
While the diamond set a record, it had been sold by Sotheby’s nearly two years earlier for over $83 million. The buyer, however, was unable to come up with the purchase price, obliging the auction house to buy it in for a reported $70 million.
The Pink Star’s record price, however, was a relatively low $1.2 million per carat, which was less than half the per carat cost of similarly graded diamonds offered at auction in recent years. For example, the 24.78 ct Graff Pink sold in 2010 for more than $1.8 million per carat, and the 14.93 ct Pink Promise sold this year for $2.13 million per carat.

The Apollo and Artemis diamonds, twin fancy colored diamonds of 14.54 cts and 16 cts, respectively, sold for $57 million at Sotheby’s Geneva auction in May. Photo courtesy of Sotheby’s
The highest bids throughout the year went, as usual, to large fancy colored diamonds – mostly pink and blue. Both colors were represented in a $57.4 million earring set offered by Sotheby’s at its May 16 auction in Geneva. The 16 ct Artemis Pink, a GIA-graded Fancy Intense pink, sold for $15.3 million, while the 14.54 ct Apollo Blue, a GIA-graded Fancy Vivid blue, went for $42.1 million.

The Pink Promise, a 14.93 ct Fancy Vivid pink diamond sold for $32.16 million at Christie’s Nov. 28 Hong Kong sale. Interestingly, the GIA-graded diamond had been recut from a 16.1 ct Fancy Intense pink. The seller, New York dealer Stephen Silver, told CNN after the sale that he wanted to improve the color grade of the diamond that had been first cut about 15 years ago.

The 14.93 ct “Pink Promise” Fancy Vivid pink diamond sold for $32.16 million at Christie’s November Hong Kong sale. Photo courtesy of Christie's Images.
Christie’s chairman for Europe and Asia, Francois Curiel said it was a strong year overall.

“Trade buyers were more active this past year, but both private collectors and dealers were consistent, active bidders,” he said. Asian buyers remained the “dominant force” in buying top gems, he said, noting that world events, such as the surge of Bitcoin and the unsettled currency markets from Brexit, have not had any noticeable effect on the auction market.

Other fancy colored diamonds sold this year include:

the 19.07 ct Fancy Light pink Le Grand Manzarin, which had been part of the French crown jewels, for $14.5 million
an 8.67 ct Fancy Intense blue, for $13.2 million
a 7.97 ct Fancy Intense blue, for $12.7 million
a twin stone Fancy Vivid blue pair, 3.36 ct and 2.71 ct, for $12.6 million
an 8.8 ct  Fancy Intense pink diamond, flanked in a ring mount by two smaller Fancy blue diamonds, for $9.7 million

And, wrapping up the year, an anonymous buyer paid $15.1 million for a 5.69 ct GIA-graded Fancy Vivid blue diamond at Sotheby’s Dec. 5 auction.

Major colorless diamonds were scarcer on the auction block this year, but two notable gems were sold:

The La Legende, a 92.18 ct heart shaped D Flawless, that drew nearly $15 million at Christie’s May Geneva sale.
The Art of De Grisogono Creation 1, a 163.41 ct D flawless, rectangle cut that was mounted  on an emerald and diamond necklace that sold for $33.7 million, a record price for a colorless diamond at auction. The per-carat price of $209,000 is high for a large D flawless but not a record. The GIA-graded diamond was cut from the 404 carat “February 4” rough found in Angola’s Lulo Mine by Lucapa Diamond Company.

Colored gemstones also attained some extreme, if not quite record high, prices. An Asian buyer paid $10.5 million for a 13.26 ct untreated Burmese ruby on Oct. 3 at Sotheby’s Hong Kong, while Christie’s sold a 15.03 ct untreated Burmese ruby for $12.94 million ($861,000 per carat) at its May Geneva auction.

Provenance, along with a lack of inclusions, helped the 18.04 ct Rockefeller Emerald achieve a record per-carat price of $305,000 at Christie’s New York auction in June. Photo courtesy of Christie’s Images
An old-line name, Harry Winston Inc., paid $5.5 million ($305,000 per carat) for an emerald carrying a lot of history: the 18.04 ct Rockefeller Emerald, offered at Christie’s June 20 New York auction. John D. Rockefeller Jr. purchased this Colombian emerald for his wife, Abby, in 1930.

Jade always tops the gemstone bill at the Hong Kong auctions and, in November, a buyer at Christie’s paid $12.3 million for a jadeite bead bracelet accented with diamonds and a small ruby.

Buyers weren’t in the mood to take everything. The 37.3 ct Fancy Intense pink Raj Pink diamond, offered by Sotheby’s at its November Geneva sale, failed to sell. Bidding started at $10 million, but halted at $14 million, less than half of the high pre-sale estimate. Also, Sotheby’s promoted a 110.92 ct L color VSI clarity diamond as the largest round brilliant ever to come to auction at the Dec. 5 New York auction, but the diamond did not find a bidder willing to meet its pre-sale estimate of $4.2 million.

The Raj Pink, a 37.30 carat GIA-graded Fancy Intense pink diamond did not sell at Sotheby’s November Geneva auction. The stone displays a strong, unmodified pink color and is said to be the largest known Fancy Intense Pink diamond in the world. Courtesy of Sotheby’s
Royal provenance is not a key to an automatic sale. Sotheby’s offered two Fancy Intense yellow diamonds, 102.54 cts and 82.47 cts respectively, at its Nov. 15 Hong Kong auction with a pre-sale price estimate of $9-14 million. The pair of diamonds had belonged to La Pavia, Countess Henckel von Donnersmarck, who in 1851 was married briefly to a Portuguese titled family. La Pavia was a courtesan and hotelier in Paris who eventually married Count Guido Henckel von Donnersmarck, a Prussian industrialist. The diamonds previously sold to a collector for $8 million in 2007, but failed to find a buyer at this sale.

Additionally, a well-publicized 5.15 ct Fancy Deep blue diamond offered Oct. 3 at Sotheby’s in Hong Kong, failed to meet its expected price of $7-9.6 million. @chapter:37 @chapter:3 @chapter:37


# Publication Year: 2021
# Title: Biogenic Carbon in Pink Corundum from Southern West Greenland
# Abstract: Figure 1. Field relationship of aluminum-rich metasedimentary rocks with ultramafic rocks at the Maniitsoq pink corundum occurrence in Greenland. Corundum is found along the boundary between these two rock types. Photo by Kristoffer Szilas.
Some of the oldest ruby is found in the southern part of West Greenland. Although the most famous locality is the Aappaluttoq deposit—where corundum is hosted by igneous rocks (N. Keulen et al., “Formation, origin and geographic typing of corundum (ruby and pink sapphire) from the Fiskenæsset complex, Greenland,” Lithos, Vol. 366–367, 2020, article no. 105536)—several smaller occurrences are found throughout the region. A number of these smaller occurrences are hosted by metamorphosed sedimentary rocks that were tectonically interleaved with ultramafic rocks (figure 1). Fluid-assisted movement of silica from the metasedimentary rocks to the ultramafic rocks and reverse movement of minor amounts of chromium during metamorphism have been proposed to cause the chemical conditions necessary for ruby growth.

Figure 2. Pink corundum from the Maniitsoq locality containing a macroscopic inclusion of graphite. Photo by Kristoffer Szilas.
Pink corundum from these smaller occurrences contains various types of mineral inclusions, most notably rutile and graphite (figure 2). Two recent studies investigated these rocks with the goals of dating the absolute timing of corundum growth, understanding the corundum formation mechanisms, and determining the origin of graphite (V. van Hinsberg et al., “The corundum conundrum: Constraining the compositions of fluids involved in ruby formation in metamorphic melanges of ultramafic and aluminous rocks,” Chemical Geology, Vol. 571, 2021, article no. 120180; C. Yakymchuk et al., “Corundum (ruby) growth during the final assembly of the Archean North Atlantic Craton, southern West Greenland,” Ore Geology Reviews, Vol. 138, 2021, article no. 104417). Samples were collected from an occurrence near the town of Maniitsoq and from a second occurrence on Storø Island to the northeast of Greenland’s capital, Nuuk.
Rutile inclusions are about 2.5 billion years old at both localities, based on uranium–lead geochronology. However, the pink corundum may be slightly older than this, given that the isotopic clock in rutile may only start sometime on the post-growth cooling history. Nevertheless, this constrains the timing of corundum growth during the final stabilization of the continental crust in the region.
This research also analyzed the carbon isotope composition of graphite to determine its origin. In general, biogenic activity modifies carbon isotopes; living organisms preferentially incorporate the lighter isotope (12C) compared with the heavier isotope (13C). Graphite from the Storø Island location was very enriched in the lighter isotope and was interpreted as a bona fide organic signature, which suggests that the graphitic carbon was originally part of a living organism. Graphite from the Maniitsoq pink corundum locality was less enriched in the lighter carbon isotope, but the isotope signature was still most consistent with a biogenic origin. Although the presence of carbon of biogenic origin is not surprising given the sedimentary nature of the host rocks, the research team modeled the chemical conditions necessary for corundum growth and suggested that the presence of graphite created the conditions in the rocks that facilitated corundum formation at the imposed depths and temperatures of metamorphism.
Although the recognition of biogenic carbon in the form of graphite in pink corundum occurrences is based on a limited number of samples, future work should be able to determine how widespread this association is in southern West Greenland. In addition, in situ analysis of carbon in graphite inclusions using secondary ion mass spectrometry would help further test the hypothesis of a biogenic origin of graphite in 2.5 billion-year-old pink corundum. @chapter:0 @chapter:0 @chapter:0


# Publication Year: 2015
# Title: Cat’s-Eye Calcite from Pakistan
# Abstract: Figure 1. This 57.60 ct calcite from Pakistan shows a cat’s-eye. Photo by Jaroslav Hyršl.

              Cat’s-eye calcites have been sold at auctions and gem shows for some years, but a gemological description of the material has not been published. Low-quality cat’s-eye calcites do exist, such as blue calcites from Mogok, Myanmar, but their chatoyancy is weak. It was very surprising, therefore, to see sharp chatoyancy on the beautiful calcite cabochon in figure 1.

The stone, purchased during the Tucson shows in February 2015, came from the Baluchistan province of Pakistan. It weighed 57.60 ct and measured 25.0 × 24.6 × 12.3 mm. It was light green and translucent, without eye-visible inclusions. The spot RI ranged from 1.48 to 1.66, and when rotated the cabochon showed a strong “blink” typical for carbonates. This is significant because the stone resembled chrysoprase; without the rotation, the measured RI in a given position might also approximate that of chrysoprase. There were no lines in the visible spectrum, the stone was inert under UV light, and its specific gravity was 2.72. Viewed in the polariscope, it remained bright, indicating a doubly refractive aggregate. Strong banding (figure 2) was present in the direction of chatoyancy, but the bands were inclined at about 20° angles. The bands were approximately 0.7 mm thick.

Figure 2. Banding in chatoyant calcite from Pakistan, as seen through the bottom of the cabochon. Photo by Jaroslav Hyršl.
Only at 40× magnification did the cause of the chatoyancy become apparent. Numerous tiny needles perpendicular to the chatoyancy were likely evidence of a columnar to needle-like texture. Other than the chatoyancy, this specimen is similar in appearance to the green and orangy yellow calcites from Pakistan that were described in the Fall 2012 GNI section (pp. 217–218). It is the opinion of both the seller and the author that this calcite is from the same locality. @chapter:8 @chapter:0 @chapter:8


# Publication Year: 2017
# Title: A Synthetic Diamond Overgrowth on a Natural Diamond
# Abstract: Figure 1. This 0.33 ct Fancy blue diamond was confirmed to be a composite of CVD synthetic type IIb diamond overgrowth on a natural type Ia substrate. Photo by Sood Oil (Judy) Chia.

Nitrogen is the most abundant defect in natural diamonds. It can be observed as single substitutional atoms or in aggregate forms. Boron, on the other hand, is a rare impurity in natural diamonds. It is very unusual to see both nitrogen and boron defects in a single diamond. GIA’s New York laboratory recently encountered this in a 0.33 ct diamond graded Fancy blue (figure 1).

The infrared spectrum revealed something very unusual: a mixed type Ia and IIb diamond (figure 2). It also showed a platelet peak at 1367 cm–1 and a hydrogen peak at 3107 cm–1. Mixed type Ia and IIb diamond occurs very rarely in nature; one was previously reported in Gems & Gemology (Spring 2009 Lab Notes, pp. 55–57). Nitrogen aggregation in this diamond was much higher, however. DiamondView images showed bluish green fluorescence in the face-up view and blue fluorescence in the face-down view (again, see figure 2). Detailed analysis using the DiamondView revealed a yellowish green fluorescence zone at the top of the crown with a sharp boundary in the crown facets (figure 2). PL spectra collected from the table and at the boundary in the crown facets showed emissions from SiV– defects at 736.3 and 736.9 nm.

Figure 2. The mid-IR spectrum on the left revealed peaks for nitrogen aggregates and boron defects, along with a platelet peak at 1367 cm–1 and hydrogen peak at 3107 cm–1. DiamondView imaging showed bluish green fluorescence in the face-up view (top right) and blue fluorescence in the face-down view (center right). The yellowish green fluorescent top layer was visible in a DiamondView image (bottom right). Images by Kyaw Soe Moe.

Although SiV– defects can be observed in a natural diamond, the combination of SiV– defects, a sharp boundary, yellowish green fluorescence, and phosphorescence suggested that the top layer was CVD synthetic diamond. The bottom diamond showed blue fluorescence but no phosphorescence in the DiamondView, consistent with natural type Ia diamond. A distinct boundary line was observed along the interface layer on the crown facets (figure 3). The presence of the overgrowth layer was also clearly revealed through inspection with a variable pressure electron microscope set up to detect both secondary electron and panchromatic cathodoluminescence (CL) emission from the sample, providing topographical and compositional information (again, see figure 3). A distinct interface was visible through the pavilion in reflected light using a fiber-optic light source. A cloud-like inclusion, trapped at the interface layer, was also observed, as well as a dark needle located at or near the interface (figure 3). A small stress halo and a natural surface could be observed in the bottom diamond. The strain pattern throughout the pavilion was consistent with natural type Ia diamond. The quality of a CVD synthetic depends on the crystallographic orientation and temperature of the seed crystal or substrate during growth. CVD synthetic diamond films have been grown on natural diamond substrates since the early 1960s (W.G. Eversole, U.S. patents 3030187 and 3030188, 1962). Methane and other carbon-containing gases were used, but graphite was deposited along with the CVD synthetic layers. In 1993, CVD synthetic layers were successfully grown on natural type IIa and Ia diamond substrates (see B.G. Yacobi et al., “Preferential incorporation of defects in monocrystalline diamond films,” Diamond and Related Materials, Vol. 2, No. 2–4, 1993, pp. 92–99). They applied a mixture of CH4 and H2 at 80 torr in a microwave plasma-assisted CVD system. Reaction between CH4 and H2 produced H atoms, which maintained an sp3-bonded surface and prevented graphitization. The temperature applied to the natural diamond substrate during the CVD growth process of the sample we studied was relatively low, as suggested by the absence of single substitutional nitrogen atoms (Ns0). It is also in agreement with Yacobi (1993), who applied temperatures of 880°C for CVD growth on type Ia {100} diamond substrates and 1200°C for type Ia {111} diamond substrates. Deposition of a boron-doped CVD synthetic film of <10 microns on a natural gem-quality diamond was reported in 2005 (Summer 2014 Lab Notes, p. 152); however, spectroscopic analysis did not show boron and SiV– defects.

Figure 3. Left: A distinct boundary line indicating an interface (marked with arrows) was seen under the microscope. A dark needle inclusion is located at or near the interface (near the center of the image). Photo by Kyaw Soe Moe; field of view 1.95 mm. Center: An electron microscope image combining secondary electron and cathodoluminescence emissions reveals the presence of an overgrowth layer. Photo by Ulrika D’Haenens-Johansson. Right: The CVD synthetic layer is approximately 80 microns thick.
Based on the growth pattern of the natural diamond, it is clear that the type IIb CVD diamond was produced in or very close to {100} orientation. The natural diamond substrate showed no observable inclusions except for a very small stress halo. The thickness of the CVD overgrowth layer was approximately 80 microns (again, see figure 3). FTIR spectroscopy is a bulk analysis, making it very hard to measure and separate IR spectra between a thin CVD layer on top and a thick diamond substrate. However, the fluorescence and phosphorescence reactions suggest that the top synthetic layer contained boron (e.g., boron-doped CVD synthetic) and the bottom diamond contained nitrogen aggregates. The thin layer of type IIb CVD synthetic diamond on the top of this stone effectively introduced Fancy blue color when viewed from its table.

This synthetic overgrowth on a natural diamond with a Fancy color grade is the first GIA has seen. Identification of colored diamonds should be performed very carefully by looking for unusual characteristics, such as a straight boundary line associated with an interface plane, and fluorescence zones with sharp edges in DiamondView images. Examination of this fancy-color composite diamond indicated that similar challenges could exist for colorless and near-colorless diamonds. @chapter:9 @chapter:1 @chapter:9


# Publication Year: 2014
# Title: Letters: Analysis of Three-Phase Inclusions in Emerald
# Abstract: In the Summer 2014 issue of Gems & Gemology (pp. 114–132), Sudarat Saeseaw and her colleagues from GIA’s Bangkok laboratory presented a study dealing with three-phase inclusions, absorption spectra, and trace-element analyses for origin determination of emeralds. Examples of three-phase inclusions were presented for samples from Zambia (the Musakashi and Kafubu deposits), the Panjshir Valley in Afghanistan, Davdar in China, and several Colombian localities (Coscuez, Muzo, Peñas Blancas, La Pita, and Chivor).

Unfortunately, the authors did not mention in their literature overview or in their discussion the various other emerald deposits which have supplied samples with three-phase inclusions. These include Nigeria (Henn and Bank, 1991); Capoeirana in Minas Gerais, Brazil (Epstein, 1989); Eastern Himalaya (Niedermayr et al., 2002); the Maria deposit in Mozambique (Vapnik and Moroz, 2002); the Lened emerald prospect in the Northwest Territories of Canada (Marshall et al., 2004); Malipo County in the Yunnan province of China (Huong, 2008); and Eidsvoll in Norway (Rondeau et al., 2008). While some of these occurrences might be of academic interest only, others such as Nigeria, Brazil, and Mozambique have supplied emeralds of gem quality to the market. These localities cannot be ignored in a research paper on origin determination and three-phase inclusions.

Although the chemical data presented in Saeseaw et al.’s table 2 were calibrated using the theoretical Si content of beryl as an internal standard, the laser ablation data show such a wide variation for the main elements that it is impossible to calculate a formula for the samples (compare, for example, the overview of chemical data for emeralds from various sources by Groat et al., 2008). Nevertheless, the authors were able to group their samples into five different categories and to present representative absorption spectra in the UV-Vis-NIR range for one sample from each group. Confusingly, four of the five spectra are labeled “E || c”, but polarized spectra are given for the ordinary ray (ω, equivalent to E ⊥ c) and the extraordinary ray (ε, equivalent to E || c), which is impossible for a primary beam with E || c.

In the spectra of several samples with low iron contents, Saeseaw et al. measured some weak to moderate absorption bands in the near infrared at 810 nm, which were assigned to bivalent iron. In the spectra of samples from Kafubu, Zambia, with higher iron contents, an additional strong absorption band at 620 nm was also assigned to Fe2+. These assignments fail to acknowledge numerous research papers dealing with the role of iron in the beryl structure, which has been established for decades. With regard to the bands mentioned at 810 nm, it has been shown that the intensities of the different iron bands in the near infrared with polarization || or ⊥ c are not directly correlated. Consequently, these absorption bands have been assigned to two different types or coordination states of iron, most likely to Fe2+ in tetrahedral and octahedral sites of the beryl lattice. Concerning the band noted at 620 nm, it has likewise been demonstrated that the intensities of the iron-related absorption bands in the near infrared are not directly correlated with the intensity of this broad band, polarized || c in the visible region around 620 nm (figure 1). Thus the broad absorption from about 600 to 750 nm in the spectra of Kafubu emeralds has been assigned to Fe2+/Fe3+ charge transfer (Schmetzer and Bank, 1981). This indicates that emeralds from Zambia’s Miku-Kafubu mining range contain, in addition to chromium as the dominant color-causing trace element, a distinct aquamarine component (figure 2). The aquamarine component is responsible for a color shift and pleochroism, especially of the color || c from green or bluish green in “ordinary” emeralds to greenish blue or blue in samples with such an aquamarine component. Emeralds from multiple sources show this phenomenon and similar absorption spectra (e.g., Schmetzer, 1988; Henn and Bank, 1991; Henn, 1992; Hänni, 1992; Moroz et al., 1999).

Figure 1. Polarized absorption spectra of emeralds from different sources. Sample A from Chivor, Colombia, represents a typical chromium-vanadium emerald spectrum without distinct iron absorption bands. Sample B from Jos, Nigeria, represents a typical chromium-vanadium emerald spectrum with an Fe2+-related absorption band (3) in the near infrared and two Fe3+ bands in the bluish violet and ultraviolet range (17, 20). Samples C (Ankadilalana, Madagascar), D (Santa Terezinha de Goiás, Brazil), and E (Miku, Zambia) represent the superimposed spectra of chromium-vanadium emeralds with distinct aquamarine components of variable intensities, wherein the aquamarine spectrum consists of two absorption bands in the near infrared (2, 3), iron bands in the bluish violet and ultraviolet (17, 20) regions, and a broad polarized absorption in the red (5). After Schmetzer (1988).

Figure 2. Polarized absorption spectra of emeralds from two different sources and an
aquamarine. Sample A, an emerald from Muzo, Colombia, displays a typical chromium-vanadium emerald spectrum without distinct iron absorption bands. Sample B, an emerald from Miku, Zambia, shows the superimposed spectra of chromium-vanadium emerald with a distinct aquamarine component. Sample C, an aquamarine from Tongafino, Madagascar,
displays a typical aquamarine spectrum with two absorption bands in the near infrared (2, 3), iron bands in the bluish violet and ultraviolet regions (17, 20), and a broad polarized absorption in the red (5). After Schmetzer and Bank (1981).
Another frequently occurring trace element in natural emeralds from various localities is vanadium. According to Saeseaw et al., vanadium absorption bands are observed in natural vanadium-bearing emeralds in the ω spectrum (equivalent to E ⊥ c) at 400 nm and in the ε spectrum (equivalent to E || c) at 654 nm. Natural vanadium-bearing, chromium-free emeralds are rare but have been documented (from Salininha, Brazil, for instance). These also reveal distinct amounts of iron, and the various bands in the absorption spectrum of this type of beryl have been assigned to vanadium and iron (Wood and Nassau, 1968). Nearly iron- and chromium-free samples have been grown synthetically; they are commercially available from Biron in Perth, Australia (Schwarz and Schmetzer, 2001), and from Tairus in Novosibirsk, Russia (Schmetzer et al., 2006; see also the summary of references describing vanadium-related absorption spectra in that paper).

Without going into the details of these spectra or discussing the possible presence of vanadium in valence states other than V3+ (see Hutton et al., 1991), it is evident that the spectrum of trivalent vanadium in beryl consists of two strong absorption bands in the visible range (figure 3). Parts of these absorption bands are split into different maxima or show various shoulders, but both absorption maxima are, in contrast to the spectroscopic characteristics noted by Saeseaw et al., present in both polarization directions, parallel and perpendicular to the c-axis.

Natural beryl from most sources reveals some traces of both vanadium and chromium. The ratio of vanadium to chromium varies considerably, especially in samples from the Colombian emerald deposits (Schwarz, 1992). Because the absorption bands of these two trace elements are found in the same spectral range, vanadium- and chromium-related absorptions are superimposed in the spectra of emeralds containing both trace elements. As a result, the different vanadium and chromium maxima are not shown individually (figure 3).

Figure 3. Polarized absorption spectra of two natural Colombian emeralds and a synthetic vanadium-bearing emerald. Sample A from Colombia shows distinctly higher chromium than vanadium contents, Cr V. Sample B shows almost equal amounts of vanadium and chromium, V ≈ Cr. Sample C, representing a Biron hydrothermally grown emerald, shows distinctly higher vanadium than chromium contents, V >> Cr. After Schwarz and Schmetzer (2001).
The vanadium-chromium ratio in natural emeralds can be approximated from the intensity of the spin-forbidden sharp chromium bands in the 600–700 nm range of the vanadium-chromium spectra. These bands are stronger in samples with distinctly higher chromium than vanadium contents (figure 3A) and become weaker in samples with almost equal chromium and vanadium contents (figure 3B). Furthermore, in samples with distinct vanadium contents, the strong absorption band in the bluish violet range at about 430 nm displays a shoulder in the ultraviolet near 395 nm, observed in both polarization directions, || or ⊥ c (see figures 3B and 3C).

Emeralds from Davdar, China, reveal appreciable amounts of vanadium and chromium (Schwarz and Pardieu, 2009), and they can be distinctly zoned, with a wide variation of vanadium and chromium contents in various growth sectors of the same crystal (Marshall et al., 2012). In Saeseaw et al.’s spectrum for an emerald from Davdar, the sharp chromium lines are distinct and the shoulder in the UV is weak (in the spectrum ⊥ c) or almost invisible (in the spectrum || c), although a vanadium to chromium ratio of about 4:1 is reported for that sample. With such a high ratio, the sharp chromium lines should be noticeably weaker and the vanadium shoulder in the UV should be more intense. Therefore, it would seem desirable to control the chemical analyses obtained by laser ablation, especially for determining the concentration of vanadium and chromium, with other non-destructive methods such as X-ray fluorescence or electron microprobe.

Dr. Karl Schmetzer
Petershausen, Germany
September 3, 2014
Reply
We appreciate the opportunity to answer Dr. Schmetzer’s interesting and informed response to our article. First of all, he has provided several helpful bibliographic references about multiphase inclusions in emeralds from a variety of geographic sources. Nevertheless, the stated purpose of our study was to compare the inclusions in emeralds from the new deposit in Musakashi (Zambia) with those from different sources in our Bangkok reference collection using standard laboratory equipment. In that regard, our article can be considered a preliminary study rather than the final word on the subject.

Dr. Schmetzer goes on to ask about our system of labeling wafers for spectroscopy. In our article, “E ∥ c” means that the wafer plane is parallel to the c-axis, which enables us to collect both ω and ε rays.

Regarding Dr. Schmetzer’s concerns about UV-Vis spectra, we focused our study on inclusions. Nevertheless, we provided some significant spectroscopic and chemical data, as these techniques are very important in emerald origin determination. Dr. Schmetzer’s specific inquiries about UV-Vis spectra and iron and vanadium contributions are beyond the scope of our article. To understand clearly how impurity affects color in beryl, we would have needed to test known samples of beryl doped with different elements. This would have taken our study in an altogether different direction.

Lastly, Dr. Schmetzer points out our inability to correlate the LA-ICP-MS chemical data with the UV-Vis spectra for one emerald from the Davdar deposit. He suggests controlling our LA-ICP-MS data with other techniques. In our opinion, the lack of correlation has more to do with the fact that these different techniques are not analyzing the same thing: UV-Vis spectroscopy is a bulk analysis, while LA-ICP-MS is a spot analysis (40 microns in diameter in this study). As a result, UV-Vis spectroscopy and LA-ICP-MS usually do not provide a perfect correlation when it comes to inhomogeneous natural emeralds with color zoning and inclusions, such as the emerald from Davdar.

Again, we thank Dr. Schmetzer for his comments and assure him that GIA plans to obtain and study more emeralds from different mining areas, to further our lab’s capacity to provide accurate origin determination reports.

Sudarat Saeseaw, Vincent Pardieu, and Supharat Sangsawong
GIA, Bangkok @chapter:10 @chapter:0 @chapter:10


# Publication Year: 1997
# Title: Benitoite from the New Idria District, San Benito County, California
# Abstract: Commercial quantities of gem-quality benitoite are known from a single location in the world, the Benitoite Gem mine in the New Idria district of San Benito County, California. A barium titanium silicate, benitoite is typically colorless to blue, and is noteworthy for its high refractive indices, moderate birefringence, and strong dispersion. Benitoite occurs in altered blue schist within serpentinite. The gem crystals formed within fractures as a result of the alteration of blue schist by hydrothermal fluids derived from the regional metamorphism of the serpentinite. An extension of the historic deposit at the Benitoite Gem mine was discovered in the spring of 1997, which should contribute to continued stability in price and supply. The gemological properties of benitoite readily identify it from similar-appearing gems. @chapter:12 @chapter:0 @chapter:12


# Publication Year: 2015
# Title: Red Heart Inclusion in Diamond
# Abstract: A unique expression of romance: Breaking the surface of this 2.00 ct diamond is a red heart-shaped inclusion. Photomicrograph by Nathan Renfro; field of view 1.58 mm.

	Diamonds, like colored gemstones, contain a variety of interesting inclusions. Although some would call them flaws, I prefer to think of them as Mother Nature’s artwork or fingerprint. I have seen inclusions resembling angels and animals of all sorts, some requiring more imagination than others. It is fascinating to think of what might have been captured inside a diamond more than two billion years ago.

	The 2.00 ct round brilliant diamond shown in figure 2 has I color, I1 clarity, and a wonderful cut. But its most remarkable feature is a red heart-shaped inclusion, identified as pyrope garnet based on microscopic examination by GIA’s Carlsbad laboratory. The inclusion is not visible to the eye but jumps out at 10× magnification. It measures approximately 140 microns across where it is exposed at the table facet. The inclusion is much larger and extends along almost half of the image frame, but the reflective interface makes it difficult to see the underlying garnet. We only see the pink color where the inclusion breaks the surface and the mirror-like interface has been removed.

	With the combination of the red heart and diamond, both universal symbols of love, this is a one-of-a-kind gem. We have named it the Forsythe diamond and plan to auction it around Valentine’s Day 2016, in keeping with the theme of romance, and part of the proceeds will go toward a local charity. How lucky are we to be able to work with beautiful gemstones containing hidden secrets just waiting to be unlocked every day. @chapter:44 @chapter:1 @chapter:44


# Publication Year: 2014
# Title: Natural Pipi Pearls from Tahiti
# Abstract: Figure 1. This parcel of rare natural pipi pearls was collected from French Polynesia. Note the exceptional golden pearl in the front with a diameter of 9.6 mm, believed to be the largest recorded pipi pearl. Courtesy of Bruno Arrighi/Croissy Pacific. Photo by Olivier Segura.

              Recently, the Laboratoire Français de Gemmologie (LFG) received a parcel of nearly 100 pearls submitted as natural pearls from Pinctada maculata. The owner (Bruno Arrighi, Croissy Pacific) specified that he had personally collected the parcel in French Polynesia during the past year (figure 1).

Pinctada maculata is a bivalve mollusk (figure 2) found in the Pacific Ocean, particularly near French Polynesia and the Cook Islands, that may produce rare “poe pipi” (better known as “pipi”) pearls. There were several unsuccessful attempts in the 1950s to produce cultured pipi specimens. Today, all such pearls are considered natural.

	Figure 2. The two valves of a typical Pinctada maculata shell specimen (interior and exterior view). Photo by Olivier Segura.
Different techniques are used to find the pearls. In one method, divers pick the largest shells of Pinctada maculata, then leave the shells on the beach in buckets full of salt water to putrefy. Three days later, the shells are selected and only the valves with blisters are kept. Deep in the bucket, one may occasionally find a few natural pearls. Kakaro (in the Paumotuan language) is considered the oldest technique for obtaining pipi pearls. During the dive, the largest shells are opened directly underwater to locate pearls.

Most pipi pearls range from orange to cream, gray, and white, but the typical and most sought-after color is a deep golden color. The size of the pearls generally ranges from 1 to 4 mm. The pearl in the forefront of figure 1 has one of the best golden colors possible. It is an exceptionally large specimen measuring 9.6 mm in diameter, which the contributors believe to be the largest size documented for a pipi pearl.

Microradiography reveals internal structures typical for natural pearls: onion-like stacking of aragonite layers possibly containing a calcitic core. Although Raman scattering, UV-visible reflectance, or UV luminescence spectrometry have helped identify the mollusk species in some cases, preliminary results with Pinctada maculata are still not conclusive. Hence, it is not possible to identify with certainty the exact mollusk from which these pearls came. @chapter:11 @chapter:4 @chapter:11


# Publication Year: 2023
# Title: Strategies to Win Over Jewelry Buyers in the U.S. Market.
# Abstract: Strategies to Captivate Jewelry Buyers in the U.S. Market
Data from Mastercard SpendingPulse, compiled by the Mastercard Economics Institute, shows that retail sales in stores and online in the United States in January expanded by 8.8% compared to the same period last year. The driving force behind consumer spending was notably in the jewelry and restaurant service sectors, which experienced significant growth.

Jewelry sales in the United States in January 2566 increased by 6.5% compared to the previous year, primarily due to consumer spending on jewelry for the Valentine's Day festival. A survey of American consumers aged 18 and above, totaling 7,728 individuals, revealed that consumers planned to purchase jewelry as gifts for Valentine's Day, averaging about $45.75 per person.

Although jewelry sales in December 2565 decreased by 5.4% compared to the previous year, it was considered a minor decline. This is because jewelry sales in December 2564 had expanded significantly by 32% compared to the year before. Retail jewelry trade figures for the United States, collected by the U.S. Department of Commerce, had a value of $91.5 billion in 2565, increasing by 5.9% compared to the previous year. This growth was driven by consumer demand for jewelry for various activities such as weddings, social events, and tourism.

Michelle Meyer, Head Economist of the Mastercard Economics Institute for the North American region, stated that the main factors driving consumer purchasing decisions in the United States are income and therefore, labor market strength is a significant support factor for consumer purchasing power in the United States. The growth in retail figures in January reflects consumer confidence in the job market, which is developing positively, and wages that have seen an increase
The unemployment rate in the United States in January 2566 was at a record low of 3.4% in 54 years. Meanwhile, the job market saw an increase of 517,000 jobs, the highest in six months. The trend of jewelry demand in the United States, gathered from leading brands, indicates that popular jewelry items this year include metal jewelry such as chains and necklaces adorned with a variety of natural pearls, sapphires, and opals. Second-hand jewelry and watches, classic-designed earrings with gold plating, men-inspired jewelry like multi-strand necklaces, cufflinks, and synthetic diamond jewelry, are also popular.

Furthermore, men's jewelry wearing has gained acceptance and popularity, contributing significantly to the expanding jewelry market. Popular men's jewelry includes chain necklaces, pendant necklaces, rings with logos or engravings, and pearl necklaces, among others. According to research by Euromonitor International, the men's jewelry market in the United States in 2564 was valued at approximately $6.5 billion, increasing by 17% compared to the previous year and almost 4% compared to 2562. This continuous growth has been ongoing since 2558 and is expected to continue in the future.

This opportunity has pushed online retailers and various brands to penetrate the growing and promising men's jewelry market. It has become increasingly popular among celebrities, athletes, and online influencers, leading jewelry brands to develop more men's jewelry lines and making jewelry more essential in daily life for all genders and ages. The distribution of jewelry products in the United States is increasingly focused on expanding into e-commerce channels
In addition to online sales, there are other supplementary services to boost sales, such as providing product information through social media and consulting services for jewelry selection by gemologists using virtual reality technology to create experiences for buyers. Besides online sales, alternative sales formats are also popular and expected to play a more significant role this year, such as organizing pop-ups, trunk sales, and selling through art gallery exhibitions.

According to data from IBIS World, online jewelry sales in the United States market in 2565 were valued at $8.69 billion, a decrease of 1.58% compared to the previous year. Analysts believe that the online jewelry market may contract in 2566 as consumers are shifting their interest towards new purchasing patterns, particularly focusing more on e-commerce platforms. Popular e-commerce platforms in the United States, such as Amazon with approximately 2 billion visitors (amazon.com), eBay with around 688.9 million visitors (ebay.com), Walmart with about 388.8 million visitors (walmart.com), Etsy with approximately 238.4 million visitors (etsy.com), among others, are gaining more popularity.

Online auction platforms in the United States, such as 1stdibs (1stdibs.com), Worthy (worthy.com), and Bidsquare (bidsquare.com), also offer opportunities for Thai jewelry and gemstones in the United States market
From discussions with importers in the United States, it was found that Thai jewelry products (OEM) still have good opportunities for market expansion in the United States. This is due to the availability of raw materials, a wide range of design options, and standardized craftsmanship, which continue to attract importers to produce goods. The trade war between China and the United States has led importers to increasingly import products from Thailand to reduce long-term risks. Furthermore, Thailand possesses skills and techniques in traditional gemstone setting that align with market demands, especially in the Antique Style market segment, which is growing significantly and highly desired by consumers.

With the quality and reputation of Thailand, Thai products have the opportunity to establish their own brands in the Luxury Market through participation in luxury exhibitions such as The Couture (Las Vegas) and Luxury JCK (Las Vegas) or leveraging key influential networks. Building such brands should be a long-term strategy to create recognition and perception that Thai products are of high quality and designed with top standards.

The diversity of consumer groups in the United States market also opens opportunities for niche market designers, especially in contemporary jewelry that is distinctive and has brand potential for market expansion. Utilizing museum channels to reach high-end customers, celebrities, and Hollywood actors with high purchasing power can further expand the market.

Designers should pay attention to designing products for holiday gifts as holiday seasons are periods of high sales and consumers have a demand for unique products. Additionally, focusing on ethics, sustainability, and environmental conservation could be another important strategy to boost confidence among Gen Millennial consumers that the company's products are socially responsible, encouraging them to buy more Thai jewelry products
 @chapter:32 @chapter:3 @chapter:32


# Publication Year: 1985
# Title: Spring 1985 G&G Book Reviews
# Abstract: “Diamond”
By Gordon Davies, 255 pp., illus., publ. by Adam Hilger Ltd., Bristol, England, 1984. US $28.00

“Gemstone Enhancement”
By Kurt Nassau, 221 pp., illus., publ. by Butterworths, London, England, 1984. US $34.95

To view the full section, download the PDF above. @chapter:35 @chapter:1 @chapter:35


# Publication Year: 2015
# Title: Thai-Myanmar Petrified Woods
# Abstract: Figure 1. Left: Petrified woods are carved and sold as ornamental gem materials, such as these specimens from the Mae Sai market near the Thai-Myanmar border. Right: A few of the cabochons from this study. Photos by Seriwat Saminpanya.

Petrified woods (figure 1, left) have long been used as a gem and ornamental material due to their beauty, luster, durability, and relative rarity. Certain minerals (mainly quartz, opal, or moganite) crystallize or precipitate in the hollow cavities and cells of the woods in a fossilization process. Fossil trading is government regulated in some countries, and gemologists should know the useful identifying characteristics of petrified woods, which can be misidentified as jasper and agate. With this in mind, the author examined Thai-Myanmar petrified wood samples, fashioned as cabochons (figure 1, right), for gemological characterization.

More than 100 Thai samples were collected from the four localities shown in figure 2: Tak, in Ban Tak-Oke (TAK); Khon Kaen, in Ban Hin Khao (BHK); Chaiyaphum, in Noen Sa Nga (CYP); and Nakhonratchasima, in Kroke Duan Ha (KDH). About 100 Burmese samples were donated by carvers from Mae Sai in Chiang Rai province (MYR), near the border of Thailand and Myanmar. Thai specimens were collected from either Quaternary gravel beds of fluvial deposits or the high-terrace sands and gravels of paleorivers. Tektite grains found in the sediments date back 700,000 to 900,000 years (P. W. Haines et al., “Flood deposits penecontemporaneous with ~0.8 Ma tektite fall in NE Thailand: Impact-induced environmental effects?” Earth and Planetary Science Letters, Vol. 225, 2004, pp. 19–28).

Thirty-eight samples (all but seven from Thailand) were tested by standard gemological methods, Raman spectroscopy, and X-ray diffraction (XRD). Thirty-seven of these came from dicotyledonous plants, indicated by vascular bundles concentrated in an outer ring of active growth. Periods of slow (winter) and fast (summer) growth create the growth rings in the trunk. One sample came from a palm tree, and had vascular bundles dispersed throughout the trunk.

Figure 2. A map showing the localities in Thailand and Myanmar where the petrified wood
samples originated. Adapted from Saminpanya and Sutherland, 2013.
The rough surfaces may have been altered and stained by soil or iron oxides, resulting in black, brown, cream, white, and red coloration. Colorless areas and different shades of brown, black, gray, white, cream, yellow, orange, and red appeared below the surface. Some samples exhibited color banding. Most Thai samples were opaque or nearly opaque; those from Myanmar were translucent and lighter in tone. The surfaces showed varying degrees of luster and fracturing. Refractive indices ranged from 1.425 to 1.543 (tested at the flat polished base of the cabochon), and specific gravities ranged from 1.963 to 2.616. Most samples fluoresced weak to moderate chalky white under long-wave UV, but some were inert or showed very weak white fluorescence.

A gemological microscope can often reveal a well-preserved wood grain structure in petrified wood samples. Studies of wood structure generally involve the transverse, tangential, and radial sections of the trunk (R.F. Evert, Esau’s Plant Anatomy: Meristems, Cells, and Tissues of the Plant Body: Their Structure, Function, and Development, 3rd ed., John Wiley & Sons, Hoboken, New Jersey, 2006, pp. 203, 292–296). A transverse section of one of the samples (figure 3) showed several tiny oval-shaped pores filled with quartz or opal (e.g., S. Saminpanya and F.L. Sutherland, “Silica phase-transformations during diagenesis within petrified woods found in fluvial deposits from Thailand-Myanmar,” Sedimentary Geology, Vol. 290, 2013, pp. 15–26). The samples also showed thin parallel rays, groups of cells oriented perpendicular to the trunk’s main axis. In some samples, the parenchyma (the most common plant tissue cells) consisted of pale lines or bands running across the rays. Others showed parenchyma surrounding a pore on the long and parallel wood grains of the tangential section, or dark-colored pores extending the length of the trunk. On the radial section, the pores ran the length of the trunk, with wood grains perpendicular to the pores.

Figure 3. Oval pores and rays (wavy white lines) are seen on a transverse section of this
petrified wood sample, and the growth rings are visible as two lines crossing the image.
Photomicrograph by Seriwat Saminpanya; field of view 10 mm.
Raman spectra were characteristic of opal (according to the RRUFF database, rruff.info), quartz, and moganite (K.J. Kingma and R.J. Hemley, “Raman spectroscopic study of microcrystalline silica,” American Mineralogist, Vol. 79, 1994, pp. 269–273). Figure 4 shows the peaks for the TAK, BHK, and CYP samples; peaks for KDH (which included opal) and MYR samples were previously presented (Saminpanya and Sutherland, 2013). Most of the quartz material displayed peaks at 354, 395–397, and 464–466 cm–1, with different colors within a sample exhibiting different peak intensities. Some samples showed only major peaks of quartz at 464–466 cm–1. Moganite was mixed with quartz in one sample apiece from CYP, KDH, and MYR, indicated by peaks at 503–506 cm–1, close to the reference peak of 501 cm–1 (Kingma and Hemley, 1994). Two KDH samples showed bands centered at 1587 and 1607 cm–1, characteristic of opal (Saminpanya and Sutherland, 2013), which was probably responsible for the weak to moderate chalky white fluorescence in some of the samples.

Figure 4. Raman spectra of petrified wood samples from Chyaphum (CYP), Tak (TAK),
and Khon Kaen (BHK) with quartz (Q) peaks at 465 cm–1. Samples from Chyaphum
show a moganite (M) peak at 503–506 cm–1.
XRD showed that the quartz peaks had an average 2Θ of 21.0, 26.7, 36.6, 39.6, 40.4, 42.5, 45.9, 50.2, and 55.0 degrees; the opal-CT peaks had an average 2Θ of 20.7, 21.7, 36.0, 44.0, and 56.9 degrees (again, see rruff.info). Quartz appeared in the XRD peaks of samples from all localities, but the opal-CT was found only in samples from KDH and MYR. The diffractogram of opal-CT in one sample from KDH appeared noisy. This may be due to its amorphous nature, though extending the XRD scan times may improve the resolution of the peaks. At this stage, XRD can only detect quartz and opal from these samples. @chapter:51 @chapter:0 @chapter:51


# Publication Year: 2019
# Title: Plume Agate from Iran
# Abstract: Figure 1. Iranian plume agate (22.45–82.03 ct) from the Ferdows agate field comes in two main varieties. The material on the left with white, green, and orange inclusions is known as “spring agate.” The stones on the right with red, yellow, and green inclusions are called “autumn agate.” Photo by Diego Sanchez.
Iran has long had a reputation as a source of quality agate, principally derived from extensive volcanic deposits throughout the country. Archaeological research on ancient tombs and finds in early human settlement sites there show that agate, chalcedony, and jasper were used not only for arrowheads and other stony instruments but also for ornamental beads and pendants.

Figure 2. Iranian “spring agate” showcases inclusions that are typically green, white, and orange. Photomicrograph by Nathan Renfro; field of view 3.78 mm.

Figure 3. A display of orangy red, green, and yellow inclusions seen in “autumn agate” from Iran. Photomicrograph by Nathan Renfro; field of view 6.00 mm.
Today, Iranian agates are primarily traded in the city of Mashhad, the largest holy city of Iran and the capital of the northwest province of Khorasan. Several varieties can be found in the market, but plume agates are the most colorful and most sought after. The samples of Iranian agate examined by the authors contained numerous plume structures in a variety of colors including green, yellow, red, white, and orange (figure 1). These plume structures are characterized by elongate billowy inclusions that can resemble clouds of smoke or feathers. The material with predominantly green, white, and orange inclusions is sold as “Bahary” (spring) agate (figure 2). The material that is principally green, yellow, and red is sold as “Paaeasy” (autumn) agate (figure 3).

Figure 4. An agate sample collected at the Aysak area in the Ferdows agate field in the southern region of Iran’s Khorasan Province. Photo by Hamid Mir-Blukey.
The samples examined were acquired in Iran by author MMS from Dr. Hamid Mir-Blukey, who has a private mining claim in the Ferdows agate field in the southern region of Khorasan (figure 4). Mining there is done mainly with primitive hand tools at or near the surface, where veins of agate are exposed as they weather out of their volcanic host rock.
While most material from this region is locally traded, the area could become an important global source for plume agate. @chapter:30 @chapter:0 @chapter:30


# Publication Year: -
# Title: Describing 58-facet Round Brilliant-Cut Diamonds at GIA
# Abstract: Today’s round brilliant-cut diamonds showcase the gem’s sparkling optics. They are the most recent expression of a cutting style that has been around for centuries. Photo by Eric Welch, © GIA, courtesy of Signed Pieces, New York

Introduction
Most consumers in today’s marketplace choose round brilliant-cut diamonds fashioned to meet modern concepts of beauty. These sparkling gems represent the collective talents of generations of skilled cutters over more than six centuries.

As diamond cuts evolved into today’s 57- or 58-facet round brilliants, styles progressed through many stages. By 1750, when the brilliant cut had developed into a style with a circular face-up outline, it had passed through many variations in facet size and proportions. These included table size, crown height, length of the lower half facets, total depth, and culet size.

This illustration shows the names and arrangement of the facets of a standard round
brilliant-cut. Illustration by Peter Johnston, © GIA
This progression has resulted in diamonds from different periods having quite distinct appearances. Over time, table facets have become larger, culets smaller, and star facets and lower half facets longer. If you rock or tilt one of the older-style gems, you’ll see a different face-up pattern of light and dark than you would with a contemporary brilliant-cut.

	Transition to Modern Brilliants

This video shows three styles of brilliants with round face-up outlines. From left to right, they are an old European cut, in place by 1750; a “transitional” brilliant from around 1880; and a modern round brilliant, in place since the 1950s. The transitional cut is labeled “circular brilliant” in the video; this is the same term now used by GIA on grading reports.The three animations show how cutting styles developed over time, causing the different face-up patterns associated with each proportion set. Animations by Al Gilbertson, © GIA
Many beautiful older diamonds present a conundrum for diamond-grading laboratories—including GIA's—because their proportions diverge from contemporary conventions. This makes it difficult to judge them against today’s aesthetic. In spite of this, there is a market for their antique beauty. In fact, some consumers cherish their different interplay with light.

Compared to a modern round brilliant cut, this older-style 1.07-ct. brilliant has a much smaller table (38.5 percent), a higher crown, shorter lower halves, and a much larger culet. Digitally modified image by Al Gilbertson, © GIA, courtesy of Michael Goldstein
Compared to a modern brilliant, older gems typically show larger face-up patterns of light and dark—what might be described as a “checkerboard” or “blocky” pattern. A modern brilliant can display a tighter mosaic of light and dark that might be described as “splintery” by those who prefer older cutting styles.

Many older round brilliants were cut between the 1870s and the 1940s. Because some served as transitions between older and more-modern styles, some trade professionals call them “transitional cuts.”

Recent high prices for precious metals have caused many pieces containing older-style diamonds to be broken up, releasing more of these beautiful gems into the market and increasing appreciation for their historic nature.

This article explains GIA’s approach to describing these beautiful older-style brilliant-cut diamonds.
The GIA Cut-Grading System for Unmodified Brilliant-Cut Diamonds
In 2005, GIA introduced a cut-grading system for unmodified round brilliant cut diamonds. The name “unmodified round brilliant” was applied to a symmetrical round cut with a regular array of 58 facets, cut to modern standards. The system was the culmination of years of research that included the results of preference testing among a wide variety of groups, including trade professionals and consumers.

GIA designed the system to assess the design quality and craftsmanship of diamonds cut in the standard round brilliant style when compared to modern preferences. The system’s grades are based on modern-day conventions and assess the proportions that yield the best combination of brightness, fire, scintillation, and pattern. There are five grades: Excellent, Very Good, Good, Fair, and Poor.

GIA’s cut scale for unmodified round brilliant-cut diamonds includes five grades. Today, the majority of the round brilliant cuts graded by GIA fit into the top two grades. This illustration shows some of the key proportion parameters that impact a round brilliant-cut diamond’s appearance. Illustration by Peter Johnston, © GIA

GIA’s cut-grading system was designed to assess the beauty and craftsmanship of modern round brilliant-cut diamonds like this 2.78-ct. gem. Photo by Robert Weldon, © GIA

This illustration shows the facet arrangement of a modern round brilliant. © GIA
The Old European Cut
Historically, GIA has described unmodified round brilliant-cut diamonds as either “round brilliant” or “old European.”

The old European cut was an early evolutionary stage in the progression toward the modern round brilliant. In general, trade professionals characterize old European cuts as having small table facets, heavy crowns, and overall “deep” or “steep” proportions.

This diamond has a small table, large culet, and short lower-half facets. These are typical of diamonds from the late 1800s. This style kept evolving until the 1950s, when it would have a larger table, longer lower-half facets, and a smaller culet. Photo by Al Gilbertson, © GIA

This illustration shows the facet arrangement of an old European brilliant cut. © GIA
Initially, GIA allowed only one exception—the old European cut—into its cut-grading system. This accommodated the distinctive proportions of diamonds cut in this classic style. Its appearance is associated with a time that predates expectations of conformity with the appearance of the modern-day round brilliant. As a result, GIA does not apply a cut grade to diamonds cut in the old European style.

GIA identifies classic old European cuts using these criteria:

 Table size: less than or equal to 53 percent
 Crown angle: greater than or equal to 40 degrees
 Lower half facet length: less than or equal to 60 percent
 Culet size: slightly large or larger

These parameters are derived from historical definitions of the old European cutting style, staff observations, and discussions with trade professionals. They ensure that these diamonds are not judged by standards that they were never fashioned to meet, and from which they would likely receive a “Fair” or “Poor” cut grade. Dealers marketing the unique appearance of these diamonds have long contended that their stones are unduly penalized by the application of modern cut-grade criteria.

In practice, if a diamond meets three out of the four criteria, it will still receive the old European cut designation on a GIA grading report. The report simply provides the gem’s measurements and grades for color and clarity. This is because GIA recognizes that, centuries ago, cutters working with natural material tried to retain as much of the original weight of the crystal as possible, so proportions often differed wildly.
Styles between Old European and Modern Round Brilliant Cuts
The old European cut was by no means the last step in the journey toward fully modern round brilliants. As cutters continued to experiment with proportions, there were many incremental steps between the old European style and the modern round brilliant.

This Tiffany & Co. brooch contains seven diamonds with an approximate total weight of five carats. They are very well-matched, “transitional” round brilliants, with the smaller table facets (52 to 54 percent); short lower half facets; and culet sizes typical of cuts created during the period from 1870 to 1950. Photo by Robert Weldon, © GIA
With growing interest in the allure of these historic cutting styles, GIA receives many diamonds in styles close to—but not quite meeting—old European criteria. Expectations for them are quite different from contemporary expectations for a modern round brilliant. This drove GIA’s decision to add a new description to address diamonds that fall outside the existing categories of both old European and modern round brilliant.
The Circular Brilliant Designation
GIA sought to address older-style diamonds that aren’t strictly Old European, but also aren’t cut to meet modern standards. Previously, GIA graders had to decide whether to call a stone a round brilliant and grade it according to contemporary standards, or to call it an old European cut and simply record color and clarity without a cut grade.

To establish judgment criteria and help define these diamonds, GIA met with members of the trade and borrowed many examples of transitional cuts from dealers. The goals were to:

 Create a new description for older-style rounds that reflects their historic cutting approach
 Prevent cut grades from being assigned to diamonds that were never fashioned to modern round-brilliant parameters
 Prevent poorly cut modern round brilliants from passing through the GIA cut-grading system without receiving grades

The GIA study uncovered a number of stones that were not classic old European cuts, but that weren’t modern round brilliants, either. They also looked neither like well cut nor poorly cut modern round brilliants.

In general, the diamonds resembled the old European cut style, but they didn’t meet GIA’s required proportion parameters for that description. Although culets were often slightly large or larger, a number of examples had medium culets. Table facet sizes ranged from 43 to 62 percent, which made this parameter difficult to use as a standard for a new category. The two characteristics that most of the stones shared were shorter lower half and shorter star facets.

Following this review, GIA decided to introduce a new description for 58-facet round brilliants. The requirements for a stone to fall into this new category are:

 Lower half length: less than or equal to 65 percent
 Star length: less than or equal to 50 percent
 Culet size: medium or larger

The new description used on GIA reports for these diamonds is “circular brilliant.” All three criteria must apply for the diamond to be designated as a circular brilliant on the GIA grading report. This designation acknowledges that the diamond is not a modern-day round brilliant, suggests a description for rounds of earlier times, and keeps the historic old European cut definition unaltered.

This illustration shows the facet arrangement of a circular brilliant. © GIA
Prior to the new circular brilliant designation, GIA graded any diamond outside these parameters as though it was a modern brilliant. As with the old European cut, reports for diamonds that fall into this new category aren’t assigned a cut grade.

These diamonds evoke a bygone romantic era. Their shorter lower halves contribute to a different pattern of light and dark than that seen in an equivalent-size modern round brilliant cut, and that some consumers cherish. By establishing the circular brilliant term and the parameters that help define it, GIA has recognized the unique nature of these antique diamonds. @chapter:41 @chapter:1 @chapter:41