Title: US Consumer Confidence Remains Strong; Alluvial Diamond Tracking and Illegal Gold Abstract: Operations at Alrosa’s Lomonosov deposit in Western Russia. Alrosa, along with De Beers, has drastically reduced sales of rough diamonds to deal with the supply overhang. Photo Russell Shor/GIA

Consumer confidence in the U.S. remained strong in August, despite the volatile stock market and increased costs stemming from the trade war with China, according to The Conference Board, which conducts the monthly Consumer Confidence Survey.
“Consumer confidence was relatively unchanged in August, following July’s increase,” said Lynn Franco, senior director of economic indicators at The Conference Board. “Consumer expectations cooled moderately, but overall remain strong. While other parts of the economy may show some weakening, consumers have remained confident and willing to spend. However, if the recent escalation in trade and tariff tensions persists, it could potentially dampen consumers’ optimism regarding the short-term economic outlook.”
Many economists believe that signs of a recession have been developing, but that positive attitudes of U.S. consumers and their spending, have kept the economy from sliding into it.
RETAIL NUMBERS

Some U.S. independent jewelers, notably at the higher end, have done well this year, but the chains continue to report lackluster results.
Signet group reported a 1% decline in same store sales for the second quarter of the fiscal year, with its Zale Corp. division posting a slight rise, while Kay Jewelers and Jared the Galleria of Jewelry posting respective declines of 3% and 4%. Sales at the Piercing Pagoda, the kiosks selling low-priced jewelry, rose 11% and its online sales, which comprise 12% of the company’s business, rose 4%.
Tiffany & Co. registered a 3% decline in same store sales worldwide and 5% in North America for the first half of the year, with Asia sales falling 1%. The company said it still expects sales will increase by single digits worldwide through the holiday period.
HONG KONG SHOW
The protests in Hong Kong have taken their toll on the region’s retail trade, particularly after the participants disrupted the airports and rail services. Sales of jewelry, watches and luxury goods are down 9% for the first seven months of the year, with steep declines in July – 24% for all retail.
The September Hong Kong Jewellery & Gem Fair will go on as scheduled, but several groups, including the Israel Diamond Manufacturers Association, have asked the organizers to postpone it. In response, the fair is offering hotel deals to lure buyers who may be hesitating to attend.
ROUGH DIAMONDS
Rough diamond sales continue to plummet in the wake of oversupplies and tight financing.
De Beers August cycle sales totaled $280 million – about 40% lower than the August 2018 cycle, but slightly higher than July’s allocation of $250 million – the smallest in four years. De Beers’ sales are down 44% from last year’s levels. In addition to purchase deferments, the company is also buying back certain goods from clients.
In a New York Times interview, De Beers’ CEO Bruce Cleaver called the situation “significant indigestion” caused by the banks’ credit squeeze and difficult geopolitics.
Alrosa was predicting that the market will stabilize once “inventories even out in accordance with market demand,” but its sales ran 35% down through the first seven months of the year; the July allocation was down 50% from the previous year while August rough sales were down 36% from the same period last year. Like De Beers, Alrosa is allowing clients to defer rough purchases until early next year.
The company announced it may trim rough sales 5% to 10% next year if market conditions persist.
ALLUVIAL DIAMOND TRACKING
Artisanal diamond miners in the West African nation of Guinea may see more returns from their diamond finds through a traceable supply initiative developed by a Belgian sustainable development organization in cooperation with the Antwerp World Diamond Center (AWDC). The diamonds produced under this program will be traced from individual miners through vetted supply chains and sold in Antwerp under the auspices of the AWDC.
Such programs are rare for miners of alluvial diamonds because the deposits tend to be spread over wide areas and are difficult to monitor. The deposits are located in the Banankoro region of the country and the Belgian organization, CAP Conseil, has been monitoring production to ensure it conforms to Maendeleo Diamonds Standards introduced by the Diamond Development Initiative (DDI) in April.
The Maendeleo Diamond Standards are made of eight specific principles covering legality, consent and community engagement, human and worker’s rights, health and safety, violence-free operations, environmental management, interactions with large-scale mining and site closure. Each of these principles is comprised of provisions defined by measurable requirements, concrete performance criteria and a list of acceptable audit evidence.
DDI developed the Maendeleo Diamond Standards in consultation with a wide range of stakeholders, including governments, industry and local civil society organizations, as well as artisanal and small-scale diamond miners in four countries of Africa and South America. DDI then conducted pilot projects in Sierra Leone in 2012 and 2013 to field-test the system, and expanded it into a full program in 2014.
ILLEGAL GOLD
Reuters has reported that Swiss gold refiners and a major financial house have identified counterfeit gold bars used in refining – kilo bars with forged Swiss bank markings – in their facilities. The bars are real gold of high fineness, but are believed to be from suspect sources, such as money launderers, criminals and sanctioned regimes.
The report estimates that at least $50 million worth of gold bars have been identified by the refiners and J.P. Morgan, but adds that it is likely that many more have slipped through the checks and into the system. Those who found the counterfeits told Reuters they are very professionally done so there are probably “way, way more” in circulation.
While there is no conclusive evidence of the source of the gold bars, authorities believe they are being made in China and sold to traders in Japan, Hong Kong and Thailand.
A second report, this from the New York Times’ “The Weekly” series, notes that illegally mined gold in Colombia is still entering the market as well. This issue was first reported four years ago. The report described the environmental and social cost of Colombia’s illicit gold mining and noted that two-third of the metal coming from the country went through illegal channels.
This issue is critically important because numerous surveys have shown that consumers increasingly care about the origins of the products they buy. At the GIA Symposium last year and at a GIA-sponsored seminar in Las Vegas last June, top executives from across the industry stressed that ethics and sustainability are now top priorities to maintain consumer trust in their brands and products. Source: GIA @topic:8


Title: Headwinds Slow 2019 Vegas Business, Lab-grown Diamonds Proliferate Abstract: The JCK Show returned to its original venue, the Sands Convention Center, in 2019. Despite the reduced traffic, exhibitors welcomed the move. Photo by Russell Shor/GIA

The U.S. stock market plunged about 7% in the two weeks leading up to the various Las Vegas shows, which ran from May 30 to June 3, injecting an air of caution into business. All told, jewelry designers and manufacturers of finished jewelry reported decent, if measured, demand, while loose diamond and gemstone dealers said business was down from last year.
Manufacturers said retailers came to buy but were cautious about placing large orders. “‘Let’s wait and see’ was the way a lot of discussions ended,” said one exhibitor in the JCK Plumb Club, an association of larger companies.
Continuing the trends of the past two years, jewelers have been incorporating more colored gems into their lines because they usually cost less than diamonds and often result in higher margins.
Judging by the jewelry designs on display at the shows, rainbows, tutti-frutti and various other wild, splashy color combinations were the major look across most price ranges. Designers favored multi-colored tourmalines, fancy colored sapphires and various colored garnets at the middle and high ends, and dyed glass and quartz in the lower price points.
Colored stone exhibitors at the American Gem Trade Association show, not surprisingly, found more calls for such material this year, especially at the lower end.

Multi-color tourmaline pieces were popular, such as these rings by Caroline at AGTA. Photo by Russell Shor/GIA
Diamond dealers, blunted by economic and political uncertainty; excess inventories, especially in sub-caraters (retailers can have their choice of thousands of such stones from online sources); and banks tightening terms of memo deals, saw less traffic and slower buying at the JCK Show.
To boost demand for diamond jewelry this fall and next year, the Diamond Producers Association (DPA) will begin aggressively targeting women who buy pieces for themselves.
The $10 million campaign #ToMeFromMe will be directed at “older millennial women.”
The DPA noted that spending by women in self-purchased jewelry averaged $1300 last year and represented 32% of U.S. diamond jewelry sales.
Despite slow diamond demand at the show, there were a number of new diamond origin tracking services at the JCK Las Vegas show. In addition to the GIA Diamond Origin Report, De Beers and Alrosa introduced their own mine-to-market diamond tracking; the Cullinan Diamond Report debuted as an identification system to track high-value, previously mined diamonds; and Sarine offered a service charting a diamond’s progress through the cutting processes.

Designers looked increasingly to affordable gems to create a bold look, such as this approximately 20 mm Baltic Amber sphere mounted on to textured silver at the Polish pavilion at JCK. Photo by Russell Shor/GIA
LABORATORY-GROWN DIAMONDS
Although calls for loose, natural diamonds were down this year, talk about laboratory-grown diamonds was even livelier than last year. About 50 companies selling lab-grown diamonds exhibited at the JCK Show, which was substantially up from last year, but prices were significantly lower. This led to intense speculation about where this market was heading.
Much of this talk was addressed at a seminar held by De Beers’ Lightbox, a line of laboratory-grown diamond jewelry the company debuted as last year’s Vegas show.
Emily Condo, brand strategy consultant for Lightbox, reported that a survey showed 44% of consumers still have not heard about laboratory-grown diamond brands and that 37% of consumers incorrectly labeled such diamonds as “simulants.”
She reported that the survey found that a majority of consumers were neutral or favorably inclined toward laboratory-grown diamonds because they offered them a choice, especially toward “lighter” occasions, such as non-romantic gifts and everyday wear. Consumers also expressed strong price resistance as prices rose: 78% said they would not spend more than $1,000 on a laboratory-grown diamond.
Lightbox, which sells its laboratory-grown diamonds for $800 per carat plus the cost of mountings, reported that after a year of selling online, 89% of those sales were for 0.5 total carat weight pieces and of those, 51% were colorless, 27% pink and 22% blue. 68% of purchasers were women buying for themselves, the majority of whom were in the 25-34-year age group.
The company noted that its production was set to reach 200,000 carats a year in the second quarter of 2020 after its factory in Oregon goes online.

A 3.01 ct Fancy Vivid orange diamond offered at JCK Luxury. Demand at the high end was muted this year as retailers took a cautious approach. Photo by Russell Shor/GIA
SOCIAL RESPONSIBILITY AND SUSTAINABLE BUSINESS PRACTICES
How best to meet consumer’s requests to have the most information about where their jewelry comes from was the topic of two industry panel discussions during the shows.
GIA presented “Embracing Sustainability Amid New Consumer Expectations” and the Responsible Jewelry Council (RJC) panel focused on corporate social responsibility and sustainable business practices.
The RJC panel included Gina Drosos, CEO of Signet Group; Jeff Corey, president of Day’s Jewelers, an eight-store chain in Maine; Raj Mehta of Rosy Blue; Eric Jens of Luxury Fintech; Feriel Zerouki, who manages De Beers Ethical Initiatives; Shekar Shah of Real gems, New York; and Iris van Veken, RJC executive director.
Participants agreed that best business practices have to begin internally with employees and customers to ensure they are “ingrained into the company’s DNA” in order to have lasting success.
“People want to believe in a company that has values,” Corey said.
Ethically sourced products occupied much of the discussion, with van Veken stressing that it was a shared responsibility across the entire value chain.
One of the most difficult areas for the incorporation of sustainable sourcing practices is artisanal mining. Shah explained that such miners are the backbone of the colored stone industry, “so they must be well taken care of.”
Zerouki added that, to empower artisanal diamond miners, De Beers developed Gem Fair, a program that gives them the best returns on their diamonds by bringing them all the way into the downstream market.
“Trust and transparency are the new equity,” van Veken stressed. “People want to have confidence that their purchases do some good.”
NEW VENUES
The JCK and AGTA shows operated in new venues this year. The JCK Show returned to the Sands Convention center, while the AGTA Show moved to the Las Vegas Convention Center, alongside the Antique and Estate Jewelry and Watch Show.
Exhibitors generally liked the changes, saying the new venues were much easier to navigate. Source: GIA @topic:8


Title: Decay Kinetics of Boron-Related Peak in IR Absorption of Natural Diamond Abstract: Figure 1. In response to UV excitation, the IR absorption spectra for a 1.01 ct Fancy gray,
nominally type IIa diamond shows a pronounced peak at 2800 cm–1, associated with
type IIb diamond and boron impurities. The intensity of the 2800 cm–1 peak decays over
several minutes. For the sake of clarity, not all collected IR absorption spectra are shown
here; the peak at 2850 cm–1 is unrelated to boron and is caused by hydrocarbon
contamination on the diamond surface.
Recently, gemologists at the National Gold & Diamond Testing Center in China found that the uncompensated boron peak at 2800 cm–1 in FTIR absorption could be induced by UV excitation and then subsequent decay, similar to the phosphorescence response often seen in type IIb diamonds (J. Li et al., “A diamond with a transient 2804 cm–1 absorption peak,” Journal of Gemmology, Vol. 35, 2016, pp. 248–252).

The Carlsbad laboratory recently received a nominally type IIa, 1.01 ct diamond with Fancy gray color. It was identified as natural and, uncharacteristically, showed a 500 nm band phosphorescence, which is typical for type IIb diamonds (S. Eaton-Magaña and R. Lu, “Phosphorescence of type IIb diamonds,” Diamond and Related Materials, Vol. 20, 2011, pp. 983–989). With UV excitation we recorded the transient 2800 cm–1 absorption (associated with uncompensated boron) observed in type IIb diamonds, and we monitored the peak’s decay (figure 1).

From the calculated area of the 2800 cm–1 absorption peak, we can determine the uncompensated boron (Bo) concentration (D. Fisher et al., “Brown colour in natural diamond and interaction between the brown related and other colour-inducing defects,” Journal of Physics: Condensed Matter, Vol. 21, 2009, 364213). Immediately after UV excitation, the diamond showed blue phosphorescence and the FTIR spectrum changed from a nominally type IIa diamond to a type IIb, with an uncompensated boron concentration of ~70 ppb (figure 2, left). An increase in the 2800 cm–1 peak upon UV excitation was previously recorded in some other type IIb diamonds as well and in a few other nominally type IIa diamonds examined by GIA, but those showed much lower values than this sample with UV excitation, with an initial increase in Bo of ~5 ppb or less. The decay of the 2800 cm–1 absorption band in the diamond studied here was well described by the non-exponential decay model 1/(1+kt), where t is the decay time and k is a constant. This equation fit the absorption decay data better than an exponential decay model or the hyperbolic decay model that describes type IIb diamond phosphorescence, 1/(1+kt)2 (K. Watanabe et al., “Phosphorescence in high-pressure synthetic diamond,” Diamond and Related Materials, Vol. 6, 1997, pp. 99–106).

Figure 2. Left: The uncompensated boron concentration for the IR absorption spectra in figure 1 were calculated and compared against several phosphorescence decay models. Right: The decay of the phosphorescence peak at 500 nm, also induced by UV excitation, was calculated and compared against the accepted model for phosphorescence. The DiamondView image shows the diamond’s blue phosphorescence.
Photoluminescence spectra were collected both with and without UV exposure using 488, 514, and 830 nm excitation. The only distinction observed between the two sets of spectra was the addition of a 3H peak (503.5 nm) when the diamond was exposed to UV radiation. The 3H peak is ascribed as an intrinsic defect containing interstitials and is often observed in PL spectra of type IIb diamonds.

Phosphorescence spectra were also recorded (figure 2, right). As expected based on prior research of diamond phosphorescence, the data did correspond well with the hyperbolic model. When boron impurities are present but are electrically compensated by other defects such as nitrogen, the 2800 cm–1 peak would not be detected and a nominally type IIa diamond would be recorded by IR absorption. However, UV excitation creates a charge transfer effect, temporarily uncompensating some of the boron so that the Bo concentration temporarily increases. This absorption decay of the 2800 cm–1 peak is most dramatic in nominally type IIa diamonds such as this sample, but has also been observed to a lesser extent in type IIb diamonds. There are several unanswered questions regarding the phosphorescence mechanism and decay kinetics in type IIb diamonds, and further study of this absorption decay will help address these issues. Source: GIA @topic:4


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. Source: GIA @topic:4


Title: Natural Colorless Type IaB Diamond with Silicon-Vacancy Defect Center Abstract: Figure 1. Emissions from the silicon-vacancy defect at 736.6 and 736.9 nm were detected in this 0.40 ct type IaB natural diamond. Photo by Johnny Leung.

The silicon-vacancy defect, or [Si-V]–, is one of the most important features in identifying CVD synthetic diamonds. It can be effectively detected using laser photoluminescence technology to reveal sharp doublet emissions at 736.6 and 736.9 nm. This defect is extremely rare in natural diamonds (C.M. Breeding and W. Wang, “Occurrence of the Si-V defect center in natural colorless gem diamonds,” Diamond and Related Materials, Vol. 17, No. 7–10, pp. 1335–1344) and has been detected in very few natural type IIa and IaAB diamonds over the past several years.

Recently, a 0.40 ct round brilliant diamond with D color and VS2 clarity (figure 1) was submitted to the Hong Kong laboratory for grading service. It was identified as a pure type IaB natural diamond. Infrared absorption spectroscopy showed low concentrations of the hydrogen peak (3107 cm–1) and N impurities in the B aggregates. Photoluminescence spectra at liquid-nitrogen temperature with 514 nm laser excitation revealed [Si-V]– doublet emissions at 736.6 and 736.9 nm (figure 2), while 457 nm laser excitation revealed the H3 (503.2 nm) emission. DiamondView fluorescence images showed blue fluorescence with natural diamond growth patterns. These gemological and spectroscopic features confirmed the diamond’s natural origin, despite the occurrence of [Si-V]– emissions. No treatment was detected.

Figure 2. The emission peaks at 736.6 and 736.9 nm from the [Si-V]– defect are shown in the type IaB diamond’s photoluminescence spectrum. Identical peak positions are detected in CVD synthetic diamonds.
Examination of this stone indicated that the [Si-V]– defect can occur, albeit rarely, in multiple types of natural diamonds. Therefore, all properties should be carefully examined in reaching a conclusion when [Si-V]– is present. Source: GIA @topic:4


Title: Long-Term Durability of CVD Synthetic Film on Diamond Abstract: Figure 1. This 0.27 ct diamond with a boron-doped CVD synthetic diamond film on the pavilion received a color grade of Fancy Dark brownish yellowish gray. The distinct color zoning seen in this photo makes it apparent that the diamond has been treated in some way and is not a natural stone. Photo by Robison McMurtry.

In 2005, a thin film (10 µm) of synthetic diamond grown by chemical vapor deposition was deposited on the pavilion of a 0.27 ct natural diamond. The CVD layer was deliberately doped with boron to create a bluish color. No subsequent polishing was performed. Rather than blue, the resulting color was a less desirable gray. This natural diamond with CVD overgrowth was then reset in a ring and worn daily by the author for the next eight years. Recently, this hybrid diamond was removed from its setting for gemological and spectroscopic characterization and to assess the current state of the CVD film.

Well-controlled durability studies have examined non-diamond coatings on diamond (e.g., A.H. Shen et al., “Serenity coated colored diamonds: Detection and durability,” Spring 2007 G&G, pp. 16–34) and nanocrystalline diamond coatings on non-diamond materials (J.E. Shigley et al., “Characterization of colorless coated cubic zirconia [Diamantine],” Spring 2012 G&G, pp. 18–30). To our knowledge, however, none have been performed on CVD diamond films grown on natural diamond. The assessment of this one sample, given the exposure a ring is usually subjected to, can indicate the long-term stability of such coatings on diamond. The expectation was that such films would remain stable, as there is no lattice mismatch in the crystal structure between the CVD synthetic film and the natural diamond. Lattice mismatch and the resulting low cohesion at the diamond/non-diamond interface typically result in moderate to very poor durability.

It was difficult to find evidence of the CVD layer using spectroscopic techniques. FTIR absorption (which generally provides data from the bulk of the diamond) revealed no CVD-specific features, only that the underlying diamond was type Ia. Using PL spectroscopy, which collects data from a limited area, it was difficult to find spectroscopic evidence of the CVD film, even when the PL data were collected in confocal mode. No CVD-related 3123 cm–1 peak was detected in IR absorption, and the silicon peak at 737 nm was not observed in PL. The best evidence of the CVD layer’s continued existence on the diamond was from its unusual appearance in visual observation (figure 1) and microscopic analysis (figure 2). The pavilion also showed electrical conductivity, which provides another indication of the boron doping.

Figure 2. This differential interference contrast image shows the irregular texture of the CVD overgrowth film on the pavilion facets of the 0.27 ct natural diamond. Each facet is a different color, and the boundaries between colors are facet junctions. Image by Nathan Renfro; field of view 246 microns.
By examining the pavilion of the diamond at high magnification, we could assess the condition of the CVD layer after eight years of daily wear. The film was still largely intact, covering the entire pavilion and containing only a few sporadic pinholes. There was no noticeable degradation at the facet junctions. The obvious color zoning in figure 1 that appears to divide the diamond into quadrants is likely due to differences in deposition and boron incorporation rates on the various facets. Recently, the diamond was annealed twice, at 600°C and 700°C for one hour each in a reducing atmosphere, in an effort to make it appear bluer. This treatment changed the color from Fancy Dark brownish yellowish gray to Fancy Dark gray.

As treatments become more sophisticated and move from the laboratory into the trade, the need for accurate detection only intensifies. Nevertheless, such semipermanent films are identifiable and reiterate the need to use both spectroscopic and traditional methods for gemological characterization. Source: GIA @topic:4


Title: Alrosa Claims Wider Role in Diamond Market with Hong Kong Auction Abstract: The highlights of the Alrosa fancy colored diamond auction in Hong Kong: A 15.11 ct Fancy Vivid orangy yellow with a minimum bid of $1.2 million and an 11.06 ct Fancy Deep purple pink that carried a reserve of $3.3 million. Both diamonds were graded by GIA. Photo Russell Shor/GIA

Alrosa, Russia’s diamond mining and marketing arm, auctioned more than 250 polished fancy colored diamonds for $9 million at a tender sale during the September Hong Kong Gem and Jewellery Fair. While the auction was important, even more significant is that it demonstrates that this once-aloof diamond producer is asserting itself into the world diamond market.

The company, the largest diamond producer by volume and second largest by revenue in 2017, publicized the sale well in advance and signaled that it plans to become more involved in diamond marketing in the future – and become the world’s major source for fancy colored diamonds.

Alrosa took the unusual step of inviting members of the trade and media to view its colored diamond collection in a meeting room in a floor above the show. In the past, it kept sales low key, inviting mainly its own clients to bid on rough and polished diamonds without outside publicity.

Evgeny Agureev, director of Alrosa’s United Selling Organization, the division that sells productions of all of Alrosa’s mines, said this was the first of what will be yearly or twice-yearly auctions of diamonds that “fill the fancy colored diamond gap” after Australia’s Argyle mine closes in 2020 or 2021. He added that the company also is looking into establishing a Russian brand for its diamonds, though those plans remain “very preliminary.”

For many years, Alrosa was a passive, though major, seller of rough diamonds. Like De Beers, it sold its rough through a network of selected clients (Alrosa Alliance) in a series of 10 sales each year, but did little to stimulate demand downstream. The company rarely participated in or contributed to industry marketing initiatives until three years ago when it joined the Diamond Producers Association (DPA). Alrosa only began to contribute in a big way to the DPA last year when it kicked in $25 million, more than one-third of the group’s total marketing budget of $70 million.

Alrosa has also opened new sales offices in New York, where it plans to auction 80 large diamonds later this year, and expanded operations in its other markets.

The highlights of the Hong Kong auction were an 11.06 ct Fancy Deep purple pink that carried a reserve of $3.3 million and a 15.11 ct Fancy Vivid orangy yellow that had a minimum bid of $1.2 million. There were 146 other fancy colored diamonds ranging in weight from just over 1 ct to 26 carats, carrying a total reserve price of $10.3 million. The majority of these were yellow, with some modified by orange or brown. Among the smaller diamonds, there were 48 fancy colored pink diamonds, most weighing between 0.3 ct to 0.5 ct. Several other lots featured smaller goods down to melee sizes in various shades of yellow. Of the 250 diamonds offered, 210 were sold.

Mining at the Lomonosov deposit in Western Russia, an important source of Alrosa’s fancy colored diamonds. Photo Russell Shor/GIA
Agureev noted that Alrosa produces 7,000 to 10,000 carats of fancy colored diamonds each year.

A majority of these fancy colors were extracted from Almazy Anabara, an alluvial operation in northwest Yakutia. An increasing number come from the newly developed Lomonosov deposit in the western portion of the country near the border with Finland. GIA reported on this deposit in the Summer 2016 issue of Gems & Gemology.

Alrosa polishes these diamonds instead of auctioning them as rough in hopes of getting better prices, said Agureev, who noted that Alrosa will polish a larger percentage of fancy colored and “special” (colorless over 10.8 cts in the rough) in the future.

“All of these diamonds were polished in our Moscow facility, where we also do our large (colorless) goods,” he said. “It is more costly [to cut diamonds there] but these goods are much less sensitive to labor costs.”

The 11.06 ct Fancy Deep purple pink diamond came from a 27.27 ct rough and took five and one-half months to process from mine to auction, according to Alrosa’s cutter. He said, in a booklet accompanying the diamond, that he needed to polish 36 millimeter-sized “windows” into the mottled surface of the rough to examine the interior of the stone.

The tender sale was well-attended through the entire show, but the final day was cancelled because of Typhoon Mangkhut, which struck Sept. 16 causing some potential buyers to miss the sale.

Alrosa also auctioned 28 polished colorless diamonds over 5 carats, the highlight being a matched pair of E color round brilliants, weighing 5.18 and 5.19 cts, respectively.

The company produced 39.6 million carats of diamonds last year, 3% higher than 2016’s total of 37.4 million carats. Alrosa’s revenues were $4.3 billion, slightly below 2016’s total of $4.5 billion. Source: GIA @topic:8


Title: Mixed-Type HPHT Synthetic Diamond with Unusual Growth Features Abstract: Figure 1. These growth tube features were visible through the table of the HPHT-grown synthetic diamond. Photomicrograph by Troy Ardon; magnified approximately 90×.

A 0.28 ct round brilliant was submitted as synthetic moissanite to the Carlsbad lab for an identification report. At first glance, synthetic moissanite seemed like a possibility. The stone had a green-yellow color and contained numerous growth tubes visible through the table (figure 1). Yet it did not show doubling in the microscope, which is a characteristic feature of synthetic moissanite. Its infrared spectrum was a match for diamond. The infrared spectrum also showed a very unusual combination of boron and nitrogen impurities at 2804 and 1130 cm–1, respectively (figure 2). These two impurities are not known to occur together in natural diamonds in measurable quantities. This was a strong indicator of synthetic origin. A DiamondView image (figure 3) confirmed that it was synthetic, grown by the high-pressure, high-temperature (HPHT) method. It is noteworthy that after the sample was removed from the DiamondView, it showed very strong blue phosphorescence that was clearly visible in ambient room lighting and persisted for several minutes.

Figure 2. The HPHT-grown synthetic diamond’s infrared spectrum shows peaks related to both boron and single nitrogen.

Figure 3. This DiamondView image shows the characteristic growth pattern of an HPHT synthetic diamond. Image by Troy Ardon.
Unless special precautions are taken, diamond synthesis will incorporate nitrogen into the lattice, which leads to a yellow bodycolor. Certain chemicals can be added to prevent the incorporation of nitrogen, and this can lead to colorless diamonds. If boron is introduced to the growth of synthetic diamonds, it will become incorporated and produce a blue bodycolor. If both boron and nitrogen are allowed to incorporate into the lattice, the blue and yellow bodycolors will combine to produce a green color (J.E. Shigley et al., “Lab-grown colored diamonds from Chatham Created Gems,” Summer 2004 G&G, pp. 128–145). Since boron is an electron acceptor and nitrogen is an electron donor, an excess of boron will compensate the nitrogen and the blue color will predominate. Because nitrogen and boron have slight preferences for different growth sectors, if the concentration of both nitrogen and boron is carefully controlled, nitrogen and boron will dominate different growth sectors. The colors will blend to create a face-up greenish color (R.C. Burns et al., “Growth-sector dependence of optical features in large synthetic diamonds,” Journal of Crystal Growth, Vol. 104, No. 2, 1990, pp. 257–279).

The growth tubes in this sample were an unusual feature, last seen in a selection of HPHT-grown synthetics several years ago at GIA’s West Coast laboratory. They appear similar to synthetic moissanite growth tubes, though there are a few key differences. Whereas the growth tubes occur in only one direction in synthetic moissanite, they could be seen growing in different directions in this synthetic diamond. The tubes in synthetic moissanite also tend to be very straight, while the ones in this sample curved and changed direction. Although this stone bore some superficial resemblance to moissanite, its gemological properties were quite different, another reminder to avoid quick sight identifications. Source: GIA @topic:4


Title: Calcium Fluoride Coating Found on 13 "Fancy" Pink Diamonds Abstract: Figure 1. These face-up images of 0.5 ct and 0.45 ct pink round brilliants are representative of the 13 coated pink diamonds submitted. Photo by Jian Xin (Jae) Liao.

Coating gemstones to alter or improve their color is the oldest known enhancement method. Early coatings, particularly on diamond, were easily detected, often visible using a 10× loupe. But advances made after World War II resulted in more durable coatings and films that were subtler and harder to detect.
A common coating was calcium fluoride (CaF2) doped with gold (Au) nanoparticles. CaF2 causes a broad absorption band at about 520 nm, similar to the band at about 550 nm that largely accounts for the pink color of natural diamonds.
Recently submitted to the East Coast laboratory for identification and grading was a group of 13 pink diamonds. The round brilliants ranged from 0.42 to 0.50 ct and had a Fancy pink to Fancy Intense pink color. The above photo shows the patchy appearance characteristic of coated diamonds. Microscopic examination using reflected light revealed obvious coating on the pavilion facets, with patchy colorless areas where it had been removed (figure 2).

Figure 2. Photomicrographs of the pink diamonds from figure 1, taken with reflected light at 80× and 100× magnification, reveal the coating applied to the pavilion facets. Photomicrographs by Paul Johnson.
The UV-visible spectra of all 13 diamonds exhibited a broad band centered at about 520 nm, not at 550 nm as expected. This band is responsible for the pink coloration, and the 520 nm position identified the coating as fluoride.

This example demonstrates that traditional treatments such as coating are still prevalent in the trade, and great care must be taken to identify them. Because coatings are not permanent, all 13 diamonds were issued identification reports disclosing the treatment. Source: GIA @topic:4


Title: Natural Blue and Black Diamonds, a Byzantine Garnet Intaglio, Yogo Sapphires, and “Kasumiga Pearls” Abstract: Characterization of diamond—both natural and synthetic—is a common thread for three of our Summer issue’s six papers. This large issue also contains a synthetic diamond chart and our new regular feature “Diamonds from the Deep,” which aims to demonstrate the value of the natural gem to science and our understanding of the earth’s depths.
However, we have much more besides diamond to offer, including Byzantine garnets, Yogo sapphires—which grace the cover—and cultured freshwater pearls from Japan’s Lake Kasumigaura.
First, lead authors Sally Eaton-Magaña, Christopher M. Breeding, and James E. Shigley review the science of naturally colored blue diamonds, which are among nature’s rarest and most valuable gems. This is the second in their series of papers focused on natural-color diamonds. Although boron impurities are top of mind for most people, the authors detail other causes of blue color in diamond, including radiation-induced defects and complex defects involving hydrogen.
Our second paper, by Karen V. Smit, Elina Myagkaya, Stephanie Persaud, and Wuyi Wang, turns the focus to Fancy Dark brown-black diamonds from Zimbabwe’s Marange deposits. Their dark appearance is caused by a combination of tiny, methane-associated graphite inclusions, graphite needles, and brown radiation stains resulting from the diamonds’ billion-year contact with radioactive minerals in the Umkondo conglomerate.
In our third paper, H. Albert Gilg, Karl Schmetzer, and Ulrich Schüssler tell a fascinating story. Using contemporary nondestructive analytical methods, they trace a Byzantine garnet intaglio back to its geographical source in Telangana State, India. The study reveals much about the ancient trading of Indian garnet.
Our fourth article, by Ahmadjan Abduriyim, profiles Japanese freshwater pearls, first cultivated in Lake Biwa, and then in Lake Kasumigaura, where most farms relocated in 1962. Although the production is limited, “Kasumiga pearls” are very attractive, displaying a variety of hues and very good luster.
Sapphires from Montana’s Yogo Gulch are renowned for their vibrant untreated blue color and high clarity. In our fifth article, Nathan D. Renfro, Aaron C. Palke, and Richard B. Berg offer a complete gemological characterization of these unique American gemstones.
Next, Sally Eaton-Magaña and Christopher M. Breeding present a new chart on the growth and characteristics of HPHT and CVD synthetic diamonds, including information on recent advances in technology that enable production of larger, higher-quality synthetics and colorless melee.
I’d also like to draw your attention to our three regular sections. Lab Notes includes entries on advances in the size and quality of synthetic diamonds. Gem News International has something for everyone: a green-blue Maxixe-type beryl, the trace element characteristics of “golden sheen” sapphire, and Ethiopian color-change garnets. G&G Micro-World includes a mushroom preserved in copal, microlite crystals in topaz, and a wurtzite phantom in quartz. This issue also presents a new regular column by Karen V. Smit and Steven B. Shirey on the value of natural diamond to science. In their inaugural entry, the authors examine how diamonds help researchers solve the enigma of water’s presence in the earth’s depths.
Finally, we’d like to remind everyone that we’re fast approaching the last chance to register for the GIA Symposium, so please go to symposium.gia.edu if you haven’t already.
Enjoy our summer edition! Source: GIA @topic:1


Title: Large, Rare Diamonds Reveal the Inner Workings of Earth’s Mantle Abstract: This is an extended abstract of the article ‘Large Gem Diamonds From Metallic Liquid in Earth’s Deep Mantle,’ published on December 16, 2016 in Science magazine. GIA Postdoctoral Research Fellow Evan Smith is the lead author of the article.

Large and exceptional gem diamonds like the famous Cullinan or Lesotho Promise tend to have a set of physical characteristics that distinguish them from other kinds of diamonds (fig 1). One of the most noted characteristics is a low nitrogen concentration, such that these diamonds are predominantly type II, although not all type II diamonds necessarily belong to this family. New research published in Science reveals that these Cullinan-like gems, dubbed "CLIPPIR" diamonds, tell us something remarkable about the deep earth1.

Figure 1: Rough CLIPPIR diamonds, from the Letseng mine, Lesotho, exemplifying large size (14 to 91 carats here), irregular shape and resorbed surfaces. Photo by Robert Weldon/GIA; courtesy of Gem Diamonds Ltd.
The new findings show that CLIPPIR diamonds may have grown from a metallic liquid in Earth’s deep mantle1. This iron-nickel metal is created and stabilized by the high pressure minerals in the deep mantle2,3. Although the amount of metal in these regions of the mantle is likely about 1% or less, it is expected to regulate and limit the availability of oxygen. The distribution and availability of oxygen is one of the key parameters governing the large-scale geologic evolution of the Earth4.

This discovery is based on inclusions. As explained in the article1, CLIPPIR diamonds tend to have few inclusions, especially in their cut and polished state, but sometimes they have small metallic inclusions trapped within them (fig 2). The metallic inclusions coexist with traces of fluid methane and hydrogen. In addition to the metallic inclusions, some CLIPPIR diamonds contain mineral inclusions that constrain the depth of origin. These inclusions show the diamonds formed at extreme depths, likely within 360–750 km in the convecting mantle. This is much deeper than most other gem diamonds, which form in the lower part of continental tectonic plates at depths of 150–200 km. This new explanation for CLIPPIR diamonds resolves one of the major enigmas in the study of diamond formation—how the world’s very best and biggest diamonds formed.

Figure 2: Polished CLIPPIR diamond (left) containing metallic inclusions. The metallic inclusions (right) are silvery in appearance and have black graphitic cracks extending from them.
The composition of the inclusions provides the story. The metallic inclusions are a solidified mixture of iron, nickel, carbon, and sulfur, also containing traces of fluid methane and hydrogen in the thin tiny space between the metallic phases and the encasing diamond1. Originally, this mix was a larger mass of molten metallic liquid in Earth’s deep mantle, from which the pure carbon crystallized to form diamonds. Small droplets of this metallic liquid were occasionally trapped within the diamonds as they grew. During cutting and polishing, parts of the diamond that contain inclusions are often trimmed off or polished away to craft exquisite gems with minimal flaws. These offcut waste diamond pieces are not normally made available for research, but a special effort was made to obtain offcuts study the inclusions in this investigation. Diamonds are one of the most valuable scientific tools for studying the deep Earth, which is otherwise completely inaccessible and hidden from our view beneath the tectonic plates.

Previous experiments and theory have predicted for many years that parts of the deep mantle below about 250 km depth contain small amounts of metallic iron and have limited available oxygen2. Now, the metallic inclusions and their surrounding methane and hydrogen jackets in CLIPPIR diamonds provide consistent, systematic physical evidence to support this prediction. Though the extent of metal distribution is uncertain, this is a key observation for our understanding of the Earth and has broad implications for the behavior of the deep Earth, including the recycling of surface rocks into the convecting mantle, and the deep storage and cycling of carbon and hydrogen in the mantle through geologic time.

Through an arrangement with Science magazine, visitors to GIA.edu can access the full text of the article ‘Large Gem Diamonds From Metallic Liquid in Earth’s Deep Mantle’ from this webpage.

View abstract
View reprint
View full text Source: GIA @topic:7


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. Source: GIA @topic:4


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. Source: GIA @topic:8


Title: 2017 Las Vegas Trade Spotty, Designers and Diamonds Lead Abstract: A 4.10 ct colorless diamond “slice” pendant with black inclusions set in white gold and surrounded by colorless to brown pavé diamonds by Rachel Boston, London. Photo courtesy Rachel Boston

The bling look continued to retreat at the annual Las Vegas shows earlier this month as retail buyers favored smaller pieces, especially those that could be layered or paired to create a personalized look.

Designers at the Couture and Luxury shows used pale-colored faceted amethyst, corundum, tanzanite and varieties of tourmaline bezel set in gold or silver. Also, designers were using diamond slices – thin-cut pieces of highly included or opaque rough diamonds – to create distinctive pieces.

Their aim, they explained, was to create jewelry that could be worn, in the words of one, “…in the gym or an evening out on the town.”

Business was spotty, but diamond traders at the main JCK show found demand better than expected. All exhibitors agreed that traffic was down, although serious buyers were there to do business.  At the Couture show, geared to higher-end exhibitors and up-scale independent retailers, some exhibitors reported strong demand, while others found the show slow going.

Luxury, the part of the JCK show geared to higher-end exhibitors, was slow across the board. Most of the buying occurred during the invitation-only portion of the show (two days before the main show opened), but exhibitors reported traffic was down from last year.

In general, retailers stuck to their open-to-buy and avoided expensive, showy pieces unless they had a specific customer in mind.

As noted, diamond dealers who went into the JCK show expecting sales declines of 10% to 15%, generally found demand slightly ahead of last year. As usual, some of the dealers who did best were those who discounted to other dealers before the show opened to raise cash.

Trading at the American Gem Trade Association show also saw diminished traffic and slow sales.

The “Candy” bracelet by VTse Jewelry is comprised of a red oval cabochon tourmaline and multi-colored sapphires. Courtesy VTse Jewelry

DIAMONDS
The Diamond Producers Association announced at the JCK show that it will up its spending on the “…real is rare...” campaign to $57 million ($50 million in the U.S.) for the fall holiday season. The funds will be used for a fourth quarter advertising campaign though various channels, as well as in-store retailer support.

In addition, ForeverMark plans to increase its diamond advertising with an emphasis on women’s self-purchase, which accounts for 31% of all diamond sales. This is up 6% from three years ago. De Beers noted that engagement rings accounted for 28% of diamond sales last year and men’s gifts to their wives comprised an additional 37% of the diamond jewelry market in the U.S.

The company, which recently acquired LVMH’s 50% share in their joint retailing venture, said its entire growth strategy would be focused on China “where heritage brands are powerful … and trusted,” according to CEO Bruce Cleaver in an interview with JCK.

Cleaver said he doesn’t see significant growth for the De Beers’ store brand in the U.S., but the retail operation will remain “an important part of (De Beers’) brand proposition.”
COLORED STONES
Gemfields, the ruby and sapphire mining company, is the object of a bidding war.

The company’s largest shareholder, Pallinghurst Resources, London, offered to buy the 53% of the company it does not own. Some analysts criticized the offer of $275.6 million in stock trades as low, even though the gem company’s stock has languished. The company earned $23.5 million on revenues of $191.1 million in 2016.

Now, however, Fosun Gold, a Chinese holding company based in Shanghai, has offered a cash price 10% above Pallinghurst’s offer and 15% above the current stock price.

Gemfields operates the Kagem emerald mine in Zambia and the Montepuez ruby mine in Mozambique. The company claims to be the single largest producer of both gemstones and also owns a 100% stake in the luxury jeweler, Faberge. Source: GIA @topic:8


Title: Alumni Marry – and Create Award-Winning Fluorescent, Phosphorescent Diamond Necklace Abstract: Mary Kay Mohs, GG, right, says gem identification was her favorite part of the GIA curriculum. “Investigating and running different tests to determine what type of gem I was working with was like solving a mystery each time!’ she says. Patrick Nelson, Mohs’ husband and business partner at Patrick Mohs Jewelry, says the curriculum prepared him for real-world business scenarios. “I can buy, design and sell as a gemologist with confidence,” he says. Photo by Carly Milbrath © Patrick Mohs Jewelry

Maggie Nelson, who moved from her rural Minnesota hometown as a young girl in 1971 to study gemology at GIA in the Los Angeles beach community of Santa Monica, couldn’t have known that her cross-country adventure would begin a family legacy.
She was armed with a single suitcase, traveling by bus with a small amount of cash from her parents – and had no idea where she would live upon arrival in California, or with whom.
“It was a big move for someone with no history in the business, from a small family farm to the big city,” says Patrick Nelson, Maggie’s son and a 2001 graduate of GIA’s Graduate Jeweler Gemologist program. “She got to the GIA campus and met students from Mexico, Japan, India and all across the country and the world, all of whom shared her interest in gems and jewelry. She quickly found other students she could room with and began her studies.”
Maggie Nelson eventually returned to Glencoe, Minnesota, where she founded and managed a successful jewelry store.
“Her story of bravery and comfort in the GIA community gave me courage, interest and excitement to do the same,” says Patrick Nelson, who left Minnesota for Southern California to earn his own GIA diploma in 2001.

The award-winning “Night Sky” necklace, left, from Patrick Mohs Jewelry features 17 18K “skipping stones” inlaid with 149 diamonds that are mapped into the shape of various constellations. The fluorescent and phosphorescent diamonds make a dramatic visual impact under black light, right. Photos by Jeff Newcomer © Patrick Mohs Jewelry
Meanwhile, Mary Kay Mohs grew up just a couple hours’ drive northwest of Nelson, in Alexandria, Minnesota. She, too, had fostered a longtime interest in gems and jewelry.
“Growing up, I was always fascinated by rocks and gems – finding them, collecting them, reading about where different gemstones are mined and how they were formed in the earth,” says Mohs. “And I’d always admired my mother’s beautiful jewelry collection.”
Mohs, who studied economics at the University of St. Thomas in St. Paul Minnesota, found that as she got closer to college graduation, she started thinking more about her lifelong enthusiasm for gemology and geology. Her jewelry-loving mother mentioned GIA as a possible road to building a career.
“When I learned about all that GIA had to offer, I thought it would be the place to follow my childhood passion and dive deeper into learning about the world of gemology,” she says.
Mohs earned her GG diploma in Carlsbad in 2004, but never crossed paths with Patrick Nelson until 2005, when they had both moved back home and were working for different locations of a Minnesota jewelry chain.
Mohs worked as a retail jewelry salesperson when Nelson noticed her, and he says he began “finding reasons” to visit that location. “I need to see one of the bench jewelers for a custom design … I need to pick up a diamond from that store … I need to speak with someone over there,” he remembers thinking.
Nelson eventually mustered the courage to ask Mohs on a date, but to his dismay, found that she had recently left the company to work as an assistant buyer and merchandise planner for fine jewelry with a large retailer. He scrambled to find her, eventually locating a co-worker who gave him her phone number. He called that day, and the next they were on a date that would lead to a personal and professional partnership.

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The couple married in 2006 and soon after, the newlyweds began hunting for gems in their down time.
“In the beginning it was a hobby, creating our art and things we liked with gems we found together,” Mohs says.
They continued to create under the name Patrick Mohs Jewelry for several years, often working at art and jewelry fairs. In 2013, the couple applied to JCK’s Rising Star Jewelry Designers contest and was selected as one of only five design houses to showcase at the JCK show in Las Vegas.
“That was the point when we began to really focus on our work together as a business, and not a hobby,” Nelson says. “Since then, we’ve traveled together to purchase gems for our jewelry creations at gem shows, made special pieces of jewelry for collectors, and continue to explore the art of jewelry-making as a couple.”
Nelson and Mohs say they are “are artists working together on every single piece we create” from their studio in Wayzata, Minnesota. They select stones and draw the designs together, then Mohs does the CAD work and Nelson casts the metal and sets the gems. “Each piece is made like a three-dimensional sculpture with no surface left untouched - we want the piece to be explored and create curiosity,” Mohs says.
They describe their jewelry as “contemporary with an organic feel,” and are inspired most by nature. Natives of the “Land of 10,000 Lakes,” they say water and waves play an especially large role in their designs – sometimes subtly, and other times as a focal point.
In one family visit to the north shore of Lake Superior, Nelson and Mohs were struck by the beauty of skipping stones into the lake with their children and admiring the stars and constellations that reflected over the water at night. That day prompted the couple to create an unusual – and reversible – necklace, the Night Sky, which features 17 18k yellow-gold “skipping stones,” inlaid with a total of 149 (2.84 total carat weight) diamonds. Each gold “stone” features diamonds that are both fluorescent and phosphorescent, allowing them to “glow” in black light and continue to glow afterward, and are arranged into the pattern of a Zodiac constellation. (Some of Nelson’s and Moh’s favorite constellations, like the Big and Little Dipper and Orion, are also included.)
The “Night Sky” necklace earned Patrick Mohs Jewelry second-place honors in the Manufacturing Jewelers and Suppliers of America’s 2017 Vision Awards. The couple says that they aim to create heirloom-worthy art, such as the Night Sky necklace, that clients will “wear and cherish” for generations.

Patrick Nelson, GJG, and Mary Kay Mohs, GG, enjoy spending time in nature with their daughter, Vivian; son, Oliver; and the family’s French Bulldog, Woody. Photo by Andy Opsahl © Patrick Nelson and Mary Kay Mohs
They agree that GIA was the ideal training ground for them to create such pieces.
“It’s truly amazing to think back at how much I learned – and still retain – from a short six-month program,” Mohs says. “All of my teachers were very knowledgeable, and each brought a unique perspective of the industry into the classroom. GIA gave me extensive practical knowledge with a laser focus on learning about gems in the trade."
Nelson, who calls his GIA education a “cornerstone” of success that he relies on for everything “from sales to design and buying,” says that he learned from instructors and classmates as much as the coursework.
"I found GIA to be the same welcoming, diverse, amazing community that my mom did – 30 years later!” he says.
The couple, who credit their mothers as being “the greatest forces” behind their accomplishments today, plan to increase their presence in more stores and galleries in the year ahead. More importantly, they hope to impact the way jewelry is perceived in the larger world of art and design.
“We hope to design and create beautiful jewelry that will be enjoyed for generations to come,” Mohs says. “And the greatest influence we could have on the industry would be helping to continue the movement of seeing jewelry design as a fine art, and collected as art.” Source: GIA @topic:11


Title: Melee Diamond Parcel Containing Nearly One-Third CVD Synthetics Abstract: Figure 1. These 101 CVD synthetic diamonds were mixed into a parcel of 323 diamond melee, representing 31.3% of the stones. Photo by Roxane Bhot.

In February 2017, a parcel containing 323 colorless to near-colorless diamond melee was submitted to the Mumbai laboratory for screening and color sorting. The average weight of each round brilliant was 0.015 ct, with an average diameter of 1.5 mm. Of this parcel, GIA’s fully automated screening and sorting system confirmed that 219 samples were natural, with the remaining 104 samples referred for further testing. Detailed analysis determined that three of the referred stones were natural, and the remaining 101 stones (31.3%) were CVD synthetics (figure 1).

This result is especially remarkable due to the type of synthetic observed. While the undisclosed mixing of HPHT synthetic diamonds in melee has become a primary concern of the diamond trade, CVD synthetics have been very rare in this size group (Fall 2016 Lab Notes, p. 307). The synthetics were color graded using the GIA melee sorting device for research purposes. The majority of the CVD synthetics were G/H (74.3%) in color, though the D–F (20.8%) and I/J (4.9%) color ranges were also represented.

Further analysis was conducted on these synthetics using Fourier-transform infrared (FTIR) and photoluminescence (PL) spectroscopy (the latter at liquid nitrogen temperature) and DiamondView imaging. Interestingly, the group included both as-grown (10.9%) and treated synthetics (89.1%), indicating that they may have been produced by different laboratories. The treated diamonds showed evidence of annealing at high temperatures for color improvement, probably under HPHT conditions. FTIR revealed that they were all type IIa, with only two samples (1.9%) showing the CVD-specific NVH0 absorption peak at 3123 cm–1. Several impurity complexes common in CVD synthetic diamonds were detected by PL spectroscopy, including NV0/– (575 and 637 nm, 100%), the 596/597 nm center (4.0%), SiV– (736/737 nm, 100%), the 883/884 nm Ni-related center (13.9%; see J.P. Goss et al., “The lattice location of Ni in diamond: A theoretical study,” Journal of Physics: Condensed Matter, Vol. 16, No. 25, 2004, pp. 4567–4578), SiV0 (946 nm, 29.7%), and H2 (986 nm, 17.8%). The presence of SiV0/– and the 596/597 nm center were particularly indicative of CVD origin, as SiV0/– centers are routinely found in CVD synthetics yet are comparatively rare in other diamond materials. The 596/597 nm center has been observed only in CVD synthetics.

Figure 2. DiamondView images of the 101 CVD synthetic diamonds showed a wide range of patterns and colors, indicative of their different growth and treatment histories. As-grown synthetics showed orange, pink, or red fluorescence (top left), while those treated by high-temperature annealing fluoresced blue or green (top right). Slightly over a third (35.6%) of the synthetics showed layers indicative of changes in growth conditions (bottom left). Those with very high Si content were dominated by blue dislocation bundles (bottom right). DiamondView images by Priyanka Dhawale and Jemini Naik.

DiamondView imaging further emphasized the variety of CVD synthetics included in this parcel. The fluorescence of the as-grown CVD synthetics ranged from orange to red to pink, as seen in figure 2 (top left), due to emissions from NV0/– centers. The other samples showed the typical blue–green fluorescence associated with high-temperature annealed CVD synthetics (figure 2, top right). In an unusual finding, layered structures suggesting abrupt changes in growth conditions—which may include stopping and restarting growth—were seen in 35.6% of the CVD synthetic melee. These abrupt changes resulted in alterations to the impurity uptakes of the material, producing the layered structures. Layer thicknesses varied but were generally about 200–500 μm, with samples often showing two or more layers intersecting their table facets (figure 2, bottom left). Such layers are regularly seen in large CVD synthetics (Winter 2015 Lab Notes, pp. 437–439), though they have not been reported for melee-sized goods. Striations and blue dislocation bundles (the latter visible in figure 2, bottom right) were common (45.5% and 19.8%, respectively); certain high-Si synthetic diamonds were dominated by these bundles. Green or blue phosphorescence was observed for 84.2% of the CVD samples.

The substantial undisclosed mixing of CVD synthetic diamonds in this parcel, approaching one-third of the stones, emphasizes the importance of routine testing of melee to identify HPHT and CVD synthetics. GIA’s automated melee screening and sorting device was able to successfully separate the natural and CVD synthetic material, providing confidence in the stones’ origin and supporting transparency in the industry. Source: GIA @topic:4


Title: Fluorescence Spectra of Colored Diamonds Using a Rapid, Mobile Spectrometer Abstract: Numerous natural-color colored diamonds from the Aurora Butterfly of Peace and other collections were studied using a new type of fluorescence spectrometer that has many advantages for gemological research, including high portability, low cost, and rapid collection times. For comparison, 10 irradiated diamonds were also studied. With only two exceptions, the natural-color diamonds could be separated into three categories—based on the peak wavelength and shape of the fluorescence spectra—that generally corresponded to their bodycolors: (1) ~450 and ~490 nm, recorded mainly for pink, yellow, and fancy white diamonds; (2) ~525 nm, mainly for green-yellow or yellow-green and brown diamonds; and (3) ~550 nm, mainly for orange, gray-green (including chameleon), and type Ia blue-gray or gray-blue diamonds. A spectrum that is anomalous for the diamond’s bodycolor may indicate that it has been treated, and in some cases, fluorescence spectroscopy can help determine diamond type.

	DATA DEPOSITORY

Map of Tested Diamonds in the Aurora Butterfly Collection
Table: Summary of Phosphorescence Results
	Submitted by Sally Eaton-Magaña
	Winter, 2007 Source: GIA @topic:4