Publish Year: 2014 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. @topic:4


Publish Year: 2013 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. @topic:10


Publish Year: 2018 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! @topic:8


Publish Year: - 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 @topic:8


Publish 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. @topic:10


Publish 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. @topic:7


Publish Year: - 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. @topic:7


Publish Year: - 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.” @topic:6


Publish Year: 2017 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. @topic:4


Publish Year: 2007 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 @topic:4


Publish Year: - Title: Tiny Inclusions Reveal Diamond Age and Earth’s History: Research at the Carnegie Institution Abstract: This sharp-edged octahedral diamond crystal nestles in kimberlite, the rock that brought it to the earth’s surface. Such crystals may preserve minerals from deep in the mantle and provide a record of temperature and pressure conditions there. Robert Weldon © GIA

                      For Dr. Steven Shirey, diamonds are very special. Not merely for their intrinsic beauty, but for the fundamental information locked within them. Information that illuminates the earth’s early history and the planet’s structure at depths hundreds of kilometers beneath our feet.

We’ve traveled to the Carnegie Institution of Washington—more specifically the Institution’s Department of Terrestrial Magnetism—to document Dr. Shirey’s work on determining the age of diamonds from many mines around the world by analyzing the tiny mineral inclusions preserved within them.

	Dr. Steven Shirey, a senior scientist at the Carnegie Institution of Washington’s Department of Terrestrial Magnetism, has a special interest in diamond—it’s his best method of glimpsing the unimaginable pressures and temperatures of the deep earth’s interior. Duncan Pay © GIA, courtesy Carnegie Institution of Washington
“Let me try to place into a broader context what the good of this diamond work is,” Shirey begins. “One of my personal goals is to take the knowledge of the age of the diamond, and the initial ratios we get from these inclusion studies and put them into the big geological picture in a systematic way. I want to look at how diamonds are distributed across continental terranes with regard to how the continent was put together.”

“I want to go back in Earth’s history to see if the pattern of diamond growth and diamond history tells us anything unique about the evolution of Earth as a planet,” Shirey says. “In itself that’s a pretty amazing concept. We’re taking these tiny grains—very, very small—and using the systematic change in chemistry to say something about our entire planet.”

	In ancient continental areas, there’s a significant keel, or downward protrusion into the mantle, where conditions are stable enough to preserve diamonds for many hundreds of millions of years. Recent discoveries show that diamonds might form beneath subduction zones at great depths, and that very rarely plumes in the earth’s mantle move them up to where kimberlites can bring them to the earth’s surface. These “superdeep” diamonds provide Shirey and other scientists a tantalizing window into the workings of the deeper mantle. Peter Johnston © GIA
This article complements the winter 2013 Gems & Gemology paper “Recent Advances in Understanding the Geology of Diamond,” coauthored by Shirey and GIA’s Dr. Jim Shigley.

Shirey is a one of a collaborative group of geoscientists from institutions all over the world using diamonds as a means to sample the deep earth. His particular specialty involves seeking out the rare individual diamonds that contain tiny and specific sulfide inclusions, painstakingly removing the inclusions and analyzing their contents—in this case, trace amounts of the radioactive isotopes of the rare metals osmium (Os) and rhenium (Re)—to determine ages on the order of billions of years.

An isotope of a chemical element is simply an atom with the same atomic number as that element, but with a slightly different mass, resulting from a different number of neutrons in its nucleus. Some isotopes are stable, but others—called radionuclides—emit radiation and decay into different isotopes over long periods of time. If scientists know the rate of radioactive decay, and have instrumentation capable of measuring the different isotopes present, they can calculate the age of an item very accurately.

This is the principle behind long-established techniques such as radiocarbon dating, which has been widely used in archaeology. Diamonds are vastly older than any archeological relic, so carbon dating—which can only date items back to around 60,000 years ago—isn’t possible.

The isotopes Shirey seeks provide a much longer reach back into the earth’s history. These radioactive isotopes are like tiny, slow-ticking clocks captured in the fabric of a diamond crystal. They decay very slowly over eons, with very long half-lives (the time it takes for a substance’s radiation to fall to half its original level). The isotope of rhenium he uses, 187Re, decays into osmium (187Os) very slowly, with a half-life of 41.6 x 109 years, or 41 billion years.

Research using the rhenium-osmium decay system proves that some diamonds are of remarkable antiquity, says Shirey. “They’re sometimes the oldest minerals we can find on the earth…up to 3.5 billion years old, whereas the earth is only 4.5 billion years old, so they’re often three-quarters of the age of the earth.”

Shirey adds that diamonds are also special because they’re the deepest minerals we can obtain as natural samples to study the earth. Unlike any other mineral, diamonds reach the surface from great depths—up to 700 kilometers (435 miles) beneath the earth’s surface—and may retain unaltered inclusions of mantle minerals within them. A diamond crystal is a “really good container” for these exotic minerals, he says, and preserves them in “pristine” form on the way to the earth’s surface.

“So in one mineral species,” he says, “you have the deepest, the oldest, and the most resistant to secondary effects mineral that you can get, so it makes them very, very unique specimens.”

	Dating Diamonds

	Dr. Shirey explains the study of radiogenic isotopes hidden inside individual diamond inclusions to determine their age and hence the age of the diamonds themselves.
Shirey tells us that the osmium-rhenium radioactive decay system allows researchers to date individual inclusions. Previous dating techniques required researchers to collect inclusions of other minerals—including garnets and zircon—from many different diamonds to obtain an age. If there was more than one generation of diamonds in the sample, you’d end up with an average age rather than the specific age.

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	This slideshow takes you through the processes Dr. Shirey uses to select natural diamonds for research and extract the sulfide inclusions from them to obtain accurate ages—often in the range of billions of years. It involves ingenious solutions to fashion the tiny diamonds into plates for study, cleave out the sulfides, separate the isotopes of rhenium and osmium by chemistry, and count the various isotopes with sophisticated laboratory instrumentation for the final age determination.

	Selecting Diamonds for Study
The process begins with suitable inclusion-bearing diamond crystals. As Shirey tells us, obtaining such diamonds for study is quite a challenge. “We have to go to a mine or some place that’s being very aggressively prospected so that they’re processing large amounts of kimberlite for diamond grade.”

Diamonds are trace minerals in the rock—kimberlite, or more rarely a lamproite as in Australia’s Argyle mine—that carried them up from the mantle. “A diamond in a kimberlite occurs at the part-per-billion level,” says Shirey, “so the average person walking around on a kimberlite is not going to find a diamond sitting there—that’s an extremely rare occurrence.”

	This diamond crystal, from Lesotho’s Letseng mine, contains a sulfide inclusion suitable for Shirey’s research. Pedro Padua © GIA, courtesy Carnegie Institution of Washington
Once researchers have traveled to suitable mining or exploration operations, where large amounts of diamond-bearing ore are produced, they have to pick through the production. Even at a mine as large as South Africa’s Venetia, only 1 in 50,000 diamonds produced might harbor the right kind of inclusion.

“In this case we’re seeking the rejects of the gem trade,” says Shirey. “Most mines have a very low frequency of inclusion-bearing diamonds to gem-quality diamonds, and so in some mines it’s almost impossible to get inclusion-bearing stones.”

	These diamond crystals, which bear sulfide inclusions decorated by rosette fracture systems, are suitable candidates for dating using the rhenium-osmium decay system. Pedro Padua © GIA, courtesy Carnegie Institution of Washington

	Preparing the Diamond for Research
Once the researchers have enough inclusion-bearing diamonds for a valid study, work can begin. “We have to get the inclusion out without breaking it,” says Shirey. “We need to recover the whole inclusion, and we also need to characterize the diamond as fully as possible.

“Our job is not just to measure the isotope composition of the inclusion, but also to get the whole picture of how the diamond formed, before we end up destroying the diamond to get the inclusion out.”

The first step is to slice the diamond very precisely across its growth zones using a diamond-cutting laser. “It would probably drive everybody in the gem business crazy to understand that we take a beautiful rough diamond and slice the center out of it,” says Shirey with a wry smile.

	Shirey designed this jig for laser cutting the diamond crystals. Duncan Pay © GIA, courtesy Carnegie Institution of Washington
“I actually had to design a device, and I went to the shop and asked if they could make it for me. And they turned it out in a day or two. We brought it back to the laser cutter and set it up, and the guys that owned the laser cutter liked it so much. It’s a little jig that has some thumbscrews that hold the diamond, just in perfect position to cut it—zip, zip, without having to reorient it—and cut three at a time.”

The wafer, with the inclusion in the middle of it, is then polished on a conventional diamond scaife. Great care must be taken to ensure the inclusions aren’t compromised or contaminated by the cutting and polishing process.

This yields a precisely oriented polished diamond plate, typically about a millimeter deep, that shows the inclusion’s position relative to the host diamond’s growth zoning. The diamond’s growth zones are especially visible using cathodoluminescence (CL) imaging. CL imaging reveals whether the diamond has a straightforward or more complex growth history.

Shirey’s colleague Dr. Jianhu Wang can also investigate the diamond plate’s isotopic composition using a secondary ion mass spectrometer (SIMS) or ion probe. The SIMS instrument allows detailed chemical analysis of the diamond’s growth zones. It can measure differences between the carbon or nitrogen isotopes across a diamond, which can establish whether the stone has a unique geologic history and what the data from the inclusion means. We will spotlight Dr. Wang’s work in a future Research & News article on the GIA website.

	Preparing Diamonds for Study

	In this sequence of videos, Dr. Shirey explains how researchers select and prepare suitable inclusion-bearing diamonds for study. The process begins with crystals that are polished into precisely oriented plates for analysis. It ends with the plates being cleaved in a specially designed “diamond cracker” to recover their sulfide inclusions for age determination using chemistry.

	Removing the Inclusion from the Diamond
Selecting, documenting, and gathering analytical data on a single diamond plate might take many weeks. From this data, however, researchers gain valuable insight into a diamond’s growth history.

At some point, though, the sulfide inclusions have to be removed from the plate for researchers to determine their age. This is the “lowest-tech” point of the process. It’s accomplished using a device Shirey calls the “diamond cracker.” This is a thick-walled hollow steel cylinder with a lid containing a piston. The diamond plate sits over a pair of tungsten carbine lathe bits, which form a platform. Shirey orients the diamond plate within the cylinder so that the portion with the inclusion lies above the gap between the two lathe bits.

On the inside of the cylinder’s lid, there’s a tungsten carbide rod bonded to the surface. Grooves inscribed on the cylinder base and the side of the lid help Shirey align it so that the rod is directly parallel and above the gap between the two tungsten carbide lathe bits in the cylinder base.

Shirey adjusts the piston in the lid so that there’s just enough play to contact the diamond without crushing it. A sharp tap on the top of the piston with a small hammer cleaves the diamond in the plane of the sulfide inclusion, releasing it.

Next, Shirey has to painstakingly search the cylinder’s interior for the inclusion. It’s often tough to find among the shards of diamond and tiny metal fragments from the tungsten carbide components or the steel wall of the diamond cracker. “The inclusion is often 100–300 microns…sometimes it’s 50 microns,” Shirey says. (One centimeter = 10,000 microns, so even a 300-micron inclusion is only 0.03 centimeters across—just 0.3 of a millimeter!)

	The tiny reflective speck at the center of the black disk is a sulfide inclusion, which has been cleaved out of a diamond plate using the “diamond cracker.” Hidden inside this tiny speck are traces of the rare elements rhenium and osmium. Pedro Padua © GIA, courtesy Carnegie Institution of Washington
At that size, simply moving the inclusion can be a big challenge: “That’s so small that static forces make it almost impossible to move the inclusion around, and so we have to be very careful not to lose the inclusion,” Shirey continues with a chuckle. “There have been times when I dropped the inclusion in the sink, and I had no recourse but to take the trap off the sink and drain the trap and start looking through all the junk in the trap, because I had so much time invested in the inclusion.”

Once Shirey recovers the inclusion, it’s transferred to a sticky black carbon disk and examined under a scanning electron microscope (SEM) to make sure it’s a sulfide inclusion and not a piece of steel or tungsten carbide from the cracker. Unlike those materials, sulfides look a little “brassy” or yellowish.

He’ll also examine the sulfide for traces of growth morphology and crystallography. Mineral inclusions can tell researchers a lot about the temperature and pressure conditions in which a diamond formed, the rocks and fluids it grew from, and whether it formed at the same time as its diamond host.

Shirey also wants to determine whether the sulfide is from an eclogitic or peridotitic source rock. Peridotitic sulfides contain higher levels of nickel and lower levels of iron. It’s important to make the distinction, Shirey tells us, because that will decide the composition of the special tracer he uses in the “wet” stage of the analysis.

His next step is to wash and rinse the inclusion with ethanol in a tiny beaker, in preparation for weighing it in an extremely sensitive electronic balance. He then carefully picks up the inclusion with a needle and transfers it to a little foil weighing boat that itself weighs a fraction of a milligram.

The weight of the inclusion is especially important, because it controls the exact amount of a special chemical tracer—called a “spike”—that Shirey has to add for the next stage of the work. The spike contains a precisely calibrated mixture of different isotopes of rhenium and osmium.

This is a standard procedure, much used in geochemistry, called isotope dilution. The sulfide inclusion contains tiny amounts of a radioactive isotope of rhenium (187Re), which decays extremely slowly over many billions of years to a stable isotope of osmium (187Os). As the rate of radioactive decay is known, it’s possible to calculate the age of the diamond based on the ratios of 187Re and 187Os present.

Isotope dilution allows researchers to estimate the amount of rhenium and osmium isotopes present—to a very high degree of accuracy—by adding a precisely calibrated solution of different isotopes of each element—the spike—and mixing it very thoroughly with the rhenium and osmium in the inclusion.

Because Shirey knows the weight of the inclusion and the exact amount of spike added, he can calculate the amounts of each rhenium and osmium isotope present from their ratios at the end of the chemistry process without having to recover everything.

Here’s an illustration of the principle behind isotope dilution: Imagine you have a large cardboard box filled with a mixture of white and a smaller number of orange Ping-Pong balls. In this simplified analogy, the cardboard box is the inclusion, the orange balls represent the osmium isotope we want to count, and the white balls stand in for everything else in the inclusion (in other words, the “matrix”).

You can calculate the number of orange balls to the highest degree of accuracy possible without counting every single one. One way is to add a known number of blue Ping-Pong balls—say 100—and mix them thoroughly with all the rest. These blue balls represent the chemical spike.

Once you’re sure all the balls are thoroughly mixed, or diluted with the other colors, take a sample of 50 balls out of the box and count the number of blue ones. From this sample, you can work out the ratio of blue balls to the total number of Ping-Pong balls in the box, as well as the orange ones you need to count. From that information, you can calculate the totals for each color very accurately. Exactly the same principle applies to the isotopes of rhenium and osmium in a diamond inclusion.

After weighing the inclusion, and adding a precisely calibrated amount of the spike, Shirey adds acid to dissolve the inclusion and thoroughly mix its constituents together with the spike.

	Separating Rhenium and Osmium

	This sequence of videos starts with Dr. Shirey weighing the sulfide inclusion recovered from the diamond. Next, he takes us through the chemistry necessary to separate the radiogenic isotopes of osmium and rhenium from the inclusion for age dating.
Once the acid has dissolved the inclusion, Shirey has to distill out the osmium and rhenium content. With osmium, this is pretty straightforward: “We distill it by vapor transport to a little button of hydrobromic acid, and the rhenium will stay back in a drop of chromic sulfuric.”

The rhenium requires a little more work: “We take this chromic sulfuric out, we reduce it, and it will go from brick red to green, and we put it then through an anion exchange column, which is like a Brita filter, but cleaned up and perfect for our work. And what it’ll do is pass everything through the column, retaining the rhenium.”

Shirey then takes the rhenium from the column and dries it down to prepare it for analysis. Now that the osmium and rhenium are separated, he can begin the final part of the process, which is to run both on sophisticated laboratory instruments called mass spectrometers. To avoid any cross contamination, each metal is run on a separate instrument, which counts the different isotopes—or masses—of each element. Shirey tells us, with something akin to relief, “From that we have the isotopic composition, and we can calculate the age…and that’s the end of the work.”

“So we do that on every inclusion,” he adds, “as long as it’s big enough to move around so that we can do the distillation—and from that, believe it or not, we get the age.”

The rhenium-osmium decay system plots as a line on a graph. Each inclusion plots as a data point, on or very close to the line.

	Researchers use the proportion of rhenium and osmium isotopes in each sulfide inclusion
	to plot a line called an isochron, which measures the decay of 187Re to187Os. Each data
	point represents an age from an inclusion and its diamond host. These diamonds from
	Canada’s Ekati mine are the oldest yet known, at 3.523 billion years (3523 Ma on the
	graph)—an astonishing age, when the earth was a quarter of its age today. The inset at
	right shows detail from the lower end of the isochron.Adapted from Westerlund (2006);
	see the Winter 2013 Gems & Gemology, figure 24, p. 211.

	Using Mass Spectroscopy

	In this video, Dr. Shirey explains the use of mass spectrometry to count the isotopes of osmium and rhenium recovered from the sulfide inclusion. This is the final stage of the analysis that began with selecting diamond crystals with suitable sulfide inclusions from working mines. Shirey and his colleagues will use the data captured on the relative amounts of each isotope to determine the age of the inclusion and therefore the diamond itself.

	Results from Research
Shirey reckons his biggest contribution to this research area, with his Carnegie colleagues, is development of the rhenium-osmium dating system, which allows dating of individual diamonds. The ages of the diamonds and the chemistry of their inclusions allow researchers to make inferences about the way continents are built and the onset of the earth’s tectonic processes.

Shirey’s early work with diamonds focused on one of the world’s best known mining areas, the ancient rocks at the heart of southern Africa, and De Beers’s mining empire: the Kaapvaal craton. The pattern of diamond occurrences and their ages from east to west across the landscape spoke to him about the structure of the deeper continent beneath his feet.

“What really turns me on about it is taking individual diamond measurements and putting them together in a large picture, so that the age distribution would tell us something fundamental on the scale of a continent—or something fundamental on the scale of the earth and a billion-year type of time history. That’s what really gets me excited,” he says.

In the case of the Kaapvaal craton, the diamonds tell Shirey that something changed in the earth’s history about three billion years ago. He and his colleagues propose that this marks the onset of what’s called the Wilson Cycle, the beginning of plate tectonics and subduction of oceanic crust. At the center of the craton lies the graveyard of an ancient ocean that closed when two continental blocks collided—one from the east and one from the west. And the diamonds in the west are different from the ones in the east.

All of the three-billion-year-old diamonds are on the west side of the craton, which agrees with Shirey’s theory about subduction of oceanic crust under the west side. By contrast, there are no diamonds older than three billion years east of the junction—or suture—between these two ancient continental blocks, “and that perfectly explains the type of diamond distribution that you see,” says Shirey.

Shirey explains that diamonds older than three billion years completely lack eclogitic inclusions. This means basalt from subducted oceanic crust had not been thrust deeply enough under the continental keel to be retained and converted into eclogite—a high-pressure metamorphic rock that hosts diamonds. After this date, scientists start to see diamonds with these types of inclusions. And that’s a big important discovery,” says Shirey.

	Canadian Diamonds Are Ancient
Another landmark discovery relates to the age of Canadian diamonds. Shirey notes that his group at Carnegie has worked on the country’s two biggest mines, Ekati and Diavik. A Ph.D. student studying Ekati’s diamonds discovered they were the oldest diamonds yet analyzed, at around 3.5 billion years old.

The chemistry of these Ekati diamonds indicated an early form of subduction. Shirey and his fellow scientists at Carnegie suggest that the subduction process forming them represents some of the earliest evidence of plate tectonics on the surface of the earth. Shirey mentions that another Ph.D. student working on diamonds from Diavik corroborated their ancient age, but found evidence they were sourced from a deep-seated plume in the earth’s mantle.

“What’s unique about the Canadian occurrences that we’ve looked at so far is their antiquity and the fact that they give us a complicated story,” says Shirey. “We think that there was more than one process to make diamonds in this early Archean period, and that’s actually a very interesting and exciting discovery.”

	Superdeep Diamonds from Brazil’s Juina Field
Superdeep diamonds are one of the most exciting finds of the last 15 years, says Shirey. These diamonds carry minerals in them that aren’t found at shallower levels, including high-pressure forms of garnet and olivine that cannot form at shallower depths. The hypothesis is that these diamonds grow from organic material carried down as deep as 700 km into the mantle by subduction. They also have a characteristic irregular internal growth structure that hints at their turbulent origin deep in the earth’s convecting mantle. Superdeep diamonds sample the earth’s mantle at greater depths than scientists have seen before, and they will undoubtedly provide insight about the way the earth recycles carbon. Shirey and a number of his Carnegie colleagues are actively collaborating with researchers at other institutions on this topic. For more details, please see his Carnegie page on superdeep diamonds and mantle convection.

	These tiny superdeep diamonds formed at significantly greater depths in the earth’s mantle than most diamonds. Here, they’re mounted for analysis in an electron microprobe. Pedro Padua © GIA, courtesy Carnegie Institution of Washington

	Rewards of the Job
Shirey tells us he loves his work because it’s so diverse: “I get to go in the field, to talk to geologists. I get to take specimens and take them apart, to design ways to cut the smallest diamonds.”

These challenges stimulate Shirey: “It’s being inventive and crafty, when it comes to manipulating the specimens, but I have to be a chemist as well—I actually had to do the development work on the chemistry. It’s all so different, which is one of the reasons I love doing what I do.”

In the end, he realizes that all this work passes for naught if it’s not communicated in a way that engages the audience. “We have to write the stuff up, communicate our results and tell the story in a way that people find interesting. At the end of the day, if no one wants to hear what you have to say, it doesn’t do any good. So if you don’t make the story interesting, no one’s going to read it.”

Shirey reminds us that research work of this kind is highly collaborative, involving scientists from different disciplines and many partner institutions around the world. He is modest about his contributions. “Most of the work is not done directly by me, but by people that I work with. Almost all the work is done by visitors to the lab, or postdocs that we’re trying to train.

“That’s actually a fun part about my job,” he continues, “I get to be a teacher and a mentor, and that turns out to be a lot of fun.” @topic:8


Publish Year: - Title: GIA Education Attracts Diverse Students to Hub of Israel Diamond Industry Abstract: Skyline of downtown Ramat-Gan, featuring the famous Israeli diamond center and the financial district surrounding it. Photo courtesy of Eldad Carin

                      Israel, one of the world’s leading rough and polished diamond trading centers, topped $5 billion in polished diamond exports in 2015. The four diamond towers of the Israel Diamond Exchange in the Tel Aviv suburb of Ramat Gan have served as the hub of the Israeli diamond industry since the 1940s. The towers house 3,000 large and small businesses employing more than 15,000 workers. The surrounding area is a technology park where many of the industry’s innovations – such as laser cutting, computer-directed cutting, rough modeling and automated polishing processes – were developed.

In mid-November of 2016, GIA instructor Ric Taylor traveled to the Ramat Gan offices of the Israel Diamond Manufacturers Association Ltd (IDMA) to teach the Institute’s five-day Diamond Grading Lab class. The class brought together a diverse group of Israeli and international students with a range of experience from performing appraisals to buying and selling rough diamonds.

“While many of the students have been buying and selling rough for years, hands-on experience with the GIA International Diamond Grading System allows them to better understand the value of the diamonds cut from this rough. They were able to gain practical experience grading diamonds according to GIA standards and better assess the value of the rough they trade,” said Taylor. “Likewise, students who were already professional appraisers before taking the lab class were able to increase their knowledge and accuracy in grading the clarity, color and cut of the diamonds they work with.”

One student from Sierra Leone, where the diamond industry is vital for the developing country, sought not only to better understand diamond quality but to explore a possible beneficiation project for his home country. His goal is to help educate those who mine and sell rough diamonds in Sierra Leone. The course enabled him to connect and network with members of the trade from not only the important diamond center of Israel, but also from around the world.

“I earned my Graduate Gemologist diploma in Bangkok and now work in a numismatic shop with my husband; we are also auctioneers and buy heirloom jewelry. Since Tel Aviv is only a three and a half hour direct flight from Geneva, I took this as an opportunity to refresh my diamond studies,” said Julie Chaponnière, a Geneva-based gemologist who participated in the class. “GIA provides just the right combination of theory and practice. With this five-day lab class, I’m better able to assess diamonds that come to us without grading reports.”

The class was sponsored by the IDMA and held in their offices in the Ramat Gan diamond district from Nov. 13-17, 2016.

Through a unique combination of hands-on training, one-on-one coaching and multimedia, students of GIA’s Diamond Grading Lab class learn techniques for grading diamonds consistently and accurately using a modern gem microscope and a jeweler’s loupe. By the end of the five-day program, participants are versed on GIA’s International Diamond Grading System™ and how it determines diamond value, the components of a GIA Diamond Grading Report, the most common diamond features, and how to operate gemological equipment. For more details about GIA education programs, contact us or call +1 760-603-4001. @topic:12


Publish Year: 2016 Title: Book Review: The Global Diamond Industry: Economics and Development Volume II Abstract: Edited by Roman Grynberg and Letsema Mbayi, 304 pp., Palgrave Macmillan, London, 2015, $115.00.

The Global Diamond Industry: Economics and Development Volume II is a compilation of papers that explore the shifting patterns of the diamond industry and the issues affecting southern African development. The editors are both leading academics specializing in development in the region: Grynberg a professor of economics at the University of Namibia and Mbayi a research fellow at the Botswana Institute for Development Policy Analysis.

	The first of the book’s two sections deals with the changing social aspects of the industry. Diamond manufacturing, once concentrated in a few centers (Antwerp, Gujarat, Tel Aviv, and New York), is now global and more culturally diverse, with Africans and Chinese widely engaged in the process. The opening paper, by Karin Hofmeester, offers a historical view, while the next, by Barak Richman, describes New York’s Jewish diamond community. The final paper in this section, by Sebastian Henn, describes how the industry shifted to India and then continued to diversify.

	The second, much larger section analyzes various factors of development. A paper by former De Beers chairman Nicky Oppenheimer addresses the “resource curse”—that valuable resources lead to corruption and conflict—by showing how diamonds have benefited Botswana and helped create a stable, prosperous nation. J. Andrew Grant describes the strengths and shortcomings of the Kimberley Process (misspelled “Kimberly” in the text), while Samuel Spiegel analyzes how Zimbabwe’s human rights violations at the Marange diamond deposits put the Kimberley Process into a crisis. Mbayi’s analysis of Botswana’s diamond cutting industry describes the skills transfers that are necessary to make such activities economic, and a paper by GIA’s Jim Shigley and another by Grynberg examine the challenges brought by treatments and synthetics.

	The volume, while certainly not exhaustive on any of the topics it addresses, offers a balanced cross-section of the development issues facing the diamond industry today. However, there is very little about the changing economics of the diamond industry—the multichannel rough market, competitive auctions, and the changing role of banks, to name a few—that ultimately have the greatest effect on its development. @topic:11


Publish Year: - Title: Spring 2016 Auction Update: Big Checks – Mega Diamonds Abstract: Christie’s sold the 14.62 ct. Fancy Vivid blue Oppenheimer Blue diamond – the largest Fancy Vivid blue ever to come up for sale – for $57.5 million on May 18. Courtesy of Christie’s

	Big diamonds – really big ones– dominated the news in May. Christie’s sold the 14.62 carat (ct.) Oppenheimer Blue for the highest price ever paid for any gemstone at auction: $57.5 million. Also, mining company Lucara Diamond Corp. auctioned one of its major finds − a 812.77 ct. rough − for over $63 million and will sell its 1,109 ct. rough diamond named Lesedi La Rona at the end of next month.

	Lucara auctioned the 812.7 ct. diamond May 8 with the winning bid going to a Dubai-based firm, Nemesis International. It was a record price for a rough diamond and unlike most diamond tenders, which are outright sales, it was for a 90% share in the stone, with the remainder held by Lucara.

	The record price will certainly buoy expectations for Sotheby’s June 29 auction of Lucara’s 1,109 ct. stone – the second largest rough diamond ever found. That auction will be very public, conducted at Sotheby’s in London. Lucara had said it expected to sell for more than $70 million, a safe assumption after the smaller of the two fetched 90% of that price.

	As if the Lesedi La Rona’s 1,109 carats (originally reported at 1,111 cts.) were not large enough, the company announced that a 374 ct. rough found the day before had once been part of it. The company said it did not know if the piece broke off naturally or during the mining process.

This 1,109 carat rough Type IIa diamond, named Lesedi La Rona, was unearthed in Botswana last year – the second largest ever found − will be sold by Sotheby’s later this year. Courtesy of Lucara Diamond

	Both Lucara diamonds came from the Kerowe Mine in Botswana; Lucara, based in Vancouver, is a full owner. Lucara, which found these two large diamonds last fall, said Kerowe had yielded eight stones larger than 100 carats during the first quarter of this year. The mine produces about 100,000 carats yearly with an average price of $649 per carat, according to the company’s annual report.

	The Dubai dealer, Nemesis, purchased a 404 ct. rough mined in Angola by Lucapa Diamond Co. earlier this year for a reported $16 million. The diamond will be sold through De Grisogono, a Swiss-based luxury jeweler headed by Fawaz Gruosi.

	Another group of significant diamonds – smaller but more colorful – are set to post price records in the final round of spring auctions.

	Christie’s sold the GIA-graded 14.62 ct. Fancy Vivid blue Oppenheimer Blue diamond in Geneva on May 18 – the largest Fancy Vivid blue ever to come up for sale. Not to be outdone, Sotheby’s Geneva sold the 15.38 ct. GIA-graded Fancy Vivid pink Unique Pink diamond, the largest diamond of that grade ever to go under the hammer. The $31.6 million price came in at the lower end of the pre-sale estimate for the diamond mined in the old Kimberley deposits in South Africa. A 5.09 ct. GIA-graded Fancy Vivid green diamond will provide the finale for the 2016 spring season. The diamond, tracked from rough to rectangle cut and mounted in a ring surrounded by Fancy pink melee, is expected to sell for $16 to $20 million.

 This 5.03 ct. Fancy Vivid green diamond, named the Aurora Green, is the largest Fancy Vivid green graded by GIA as of this year. It will be auctioned May 31 at Christie’s Hong Kong where it is expected to sell for $16-$20 million. Photo courtesy of Christie’s

	ROUGH DIAMONDS

	De Beers’ chairman Philippe Mellier has noted that the company is “adopting a prudent mindset” for its rough diamond sales through the middle of the year. The company sold $660 million at its April sight (now called cycle) on top of about $1.2 billion at its two previous cycles in 2016. The company, however, announced its production for the year will be down about 10% – 26 to 28 million carats – for the year.

	De Beers remained profitable through a difficult 2015, earning $571 million (half of its 2014 profits, however), but its parent company Anglo American continues to struggle with high debts incurred by other projects that commenced when Chinese demand for resources seemed insatiable. Anglo is hoping to realize some $150 million from the sale of De Beer’s long-time Charterhouse Street headquarters.

	Alrosa, the world’s largest producer by volume, estimated its yearly production will be 37 to 39 million carats, equal, to or slightly lower than 2015 levels. The company withheld 22 millions carats from the market last year as demand collapsed in the second half. The company stated that it wants to sell down the stocks it accumulated last year, while also selling new production, but keeping prices stable. @topic:7


Publish Year: - Title: Large HPHT-Grown Synthetic Diamonds Examined in GIA’s Hong Kong Laboratory Abstract: These two large synthetic diamonds were produced using HPHT growth methods by the Russian firm New Diamond Technology. The 4.30 ct specimen on the left has D color and SI1 clarity. On the right is a 5.11 ct sample with K color and I1 clarity. Photo by Wuyi Wang.

                      Over the last decade, the jewelry industry has seen rapid improvement in the quality of synthetic diamond grown by the CVD (chemical vapor deposition) method. Colorless and near-colorless CVD synthetics with sizes slightly larger than 3.00 cts. have been reported. GIA’s Hong Kong laboratory recently examined two large synthetic diamonds created using the HPHT (high-pressure, high-temperature) method that demonstrated parallel progress in the two growth technologies. These samples, shown above, were produced in Russia by New Diamond Technology.

The first was a 4.30 ct cushion-shaped with D color and a clarity grade of SI1, based on three small clusters of metallic inclusions. The other was a 5.11 ct cut-cornered rectangular modified brilliant. It had K color and a clarity grade of I1, the result of a few metallic inclusions and two small fractures in the girdle area. Neither one showed reaction to long-wave UV radiation. When they were exposed to short-wave UV, a medium to strong green-yellow fluorescence was observed. Both showed strong yellow-green phosphorescence lasting more than 20 seconds. One noteworthy feature was the absence of pinpoint inclusions, which are common in HPHT synthetic diamonds and often distributed throughout the crystal.

Absorption spectra in the infrared region demonstrated these were type II diamonds, with no absorption band detected in the one-phonon region (approximately 1350–1000 cm–1) where nitrogen impurities occur. A very weak 2800 cm–1 band was attributed to trace substitutional boron. A higher boron concentration was recorded in the D-color synthetic diamond (7 ± 1 ppb, compared to 1.2 ± 0.2 ppb). Photoluminescence spectra collected at liquid-nitrogen temperature with varying laser excitations revealed an emission doublet at 736.6/736.9 nm from the silicon-vacancy defect, and an 882.7/884.4 nm doublet from the well-known Ni-related defect. Very weak emissions from nitrogen-vacancy centers at 575.0 and 637.0 nm were detected only in the K-color sample. Besides metallic inclusions, another important identification feature of HPHT synthetics is fluorescence. Typical fluorescence patterns showing multiple-sector growth were observed in both samples.

These two diamonds were disclosed as HPHT synthetic when submitted for examination. Tested using the GIA DiamondCheck device, both were referred for further testing. Gemological observations and spectroscopic features confirmed they were HPHT synthetics.

Examination of these improved HPHT synthetic diamonds, the largest synthetic diamonds GIA has examined so far, demonstrated significant progress in this growth technology. In addition to their use as gem materials, crystals of this size have many potential industrial applications. @topic:4


Publish Year: - Title: GIA Grad Makes Headline-Grabbing Fancy Diamond Buys Abstract: Shmulik Polnauer, GG, admires the 1.68 ct Prosperity Pink diamond. Polnauer has won more than 40 diamonds from Rio Tinto’s Argyle Pink Diamond Tender in the last five years. Photo courtesy Leibish & Co.

                      Plenty of customers step up to the counter to purchase diamonds every year, but when Shmulik Polnauer does, it often earns him headlines.

To be fair, Polnauer is not exactly the average jewelry consumer – he’s a GIA Graduate Gemologist and the 33-year-old chief diamond buyer for Israel’s Leibish & Co. He has won more than 40 pink diamonds from Rio Tinto’s Argyle Pink Diamond Tender alone in the last five years; his recent purchases also including the newsmaking 1.68 carat (ct) Prosperity Pink, the 2.02 ct Pink Promise and the 3.37 ct Purple Orchid – offered at $1 million, $1.5 million and $4 million, respectively.

	The Pink Promise as a 4.96 ct rough (left) and a 2.02 ct. finished, cushion-shaped Fancy Vivid Purplish Pink diamond (right). Shmulik Polnauer won the diamond, which was found in South Africa’s KAO mine, at the Fusion Tender in Antwerp in November 2012. “We spent over four months assessing and then polishing” the stone, Polnauer says. The Pink Promise, offered at $1.5 million at the 2013 Hong Kong International Jewelry Show, sold the same week. Photo courtesy Leibish & Co.
Polnauer, a veteran of the Israeli Defense Force, has made of career of learning to analyze diamonds and “see beyond the stone.”

“I try to identify the smallest, most minute details that enable us to improve the color, cut and sometimes the clarity of the stones,” he says.

Polnauer’s father, Leibish Polnauer, began his own gem and jewelry career in the 1970s, working his way from diamond polisher to salesman before opening his own firm – Leibish & Co. – in Ramat Gan, Israel, in 1979. Shmulik Polnauer would often tag along with his father to work, and as a young man, worked summers in the family business.

	Shmulik Polnauer (left), Leibish & Company’s chief diamond buyer, and his father,
	Leibish Polnauer. The elder Polnauer founded his namesake company in Ramat Gan,
	Israel, in 1979. Photo courtesy Leibish & Co.
After serving as an officer in the Israeli Defense Force, Polnauer returned home and joined Leibish & Co., which focuses on natural fancy colored diamonds. He found that the more he worked with the stones, the more he wanted to learn – and his familiarity with the diamond trade meant he was also well-acquainted with GIA and the value of its diamond grading reports.

“I saw my future in diamonds,” he says, “and understood that with the right education, at the best gemological institution in the world, I would be able to increase my chances of success.”

Just a year after joining the family business, Polnauer took a six-month leave to study at GIA’s London campus – where he was “pleasantly surprised” at the rigor and challenge of the gemology coursework, which was even “more educational and professional” than he expected, especially for someone with a previous background in diamonds.

“It was quite challenging,” Polnauer says. “I gained a much better and clearer understanding of individual diamond characteristics, and a significant amount of knowledge about gemstones, too.”

Polnauer graduated from GIA with his GG diploma in 2004.

“Without any doubt whatsoever, having completed the GIA coursework, I felt 100 percent more confident when dealing with diamonds, and more comfortable working in the trade,” he says. “Having a better understanding of the product enables you to seek out the right stones for purchase and compare them to other options available on the market.”

Polnauer, who lives in Rechovet, Israel, with his wife, Rinat, and three children, realized early in his career that he was most intrigued with the “magic” of fancy colored diamonds, and enjoyed recognizing “underappreciated stones” and their potential for improvement. He says that knowing the market well is crucial to his – or anyone’s – success in the gem and jewelry industry, as well as learning to think a few steps ahead.

He advises incoming GIA students to follow a similar course.

“Figure out specifically what interests you, focus on your specialty, invest your time in learning the market,” he says. “And clear your schedule. Because GIA is serious work.”

	Shmulik Polnauer won the Prosperity Pink Diamond (left) at the 2011 Argyle Pink Diamond Tender as a 1.71 ct, Fancy Intense Purplish Pink, radiant-cut diamond. After deciding to repolish the stone to improve its color intensity, Polnauer brought the Prosperity Pink to a 1.68 ct, Fancy Vivid Purplish Pink. It was offered for $1 million. The Purple Orchid (right), offered for $4 million at the 2014 Hong Kong Jewellery & Gem Fair, came from a South African mine and weighed 4-plus carats. Polnauer bought the rough stone in India and transformed it to a 3.37 ct, Fancy Intense Pinkish Purple VS2 diamond. Photo courtesy Leibish & Co. @topic:12