Title: Kyanite: A Rare Blue Guest in Diamond Abstract: A deep blue kyanite crystal inside a 2.23 ct diamond identifies its host as being of eclogitic origin. Photomicrograph by Nathan Renfro; field of view 2.18 mm.

Few landscapes in the micro-world of minerals are as exciting as those encountered within diamonds, which can tell us much about the world from which this most precious of gems originates: the otherwise inaccessible deep earth (J.I. Koivula and E.A. Skalwold, “The microworld of diamonds: Images from the earth’s mantle,” Rocks & Minerals, Vol. 89, No. 1, 2014, pp. 46–51). Of the minerals found as inclusions in diamonds, a few are very deeply colored, due to their strong saturation at any dimension (e.g., red chromium-containing pyrope or a vivid green diopside) or their relatively large size (e.g., olivine crystals that are less saturated with diminishing size, ultimately becoming colorless). While ruby is considered one of the rarest inclusions encountered in diamond, inclusions that are vivid blue hold a similar rank. When discovered in routine examination of a diamond gemstone, they elicit not just breathless appreciation for their exquisite hue, but also anticipation of what they might turn out to be.

So it was with great interest that we examined an intensely saturated rounded blue inclusion within a 2.23 ct diamond (see above), a rarity greatly exceeding that of a flawless diamond gemstone. In this case, Raman analysis was used to non-destructively identify the crystal as kyanite, a mineral that occurs only in diamonds of eclogitic origin. This crystal is remarkable for its size (about 0.60 mm long), which in part accounts for its deep color; smaller crystals range from pale blue to colorless. Such colored mineral inclusions in diamonds should not be regarded as imperfections, but rather as hallmarks of beauty and as windows into our planet’s deepest secrets. At the very least, they are a compelling invitation from the micro-world to embark on a fascinating scientific adventure. Source: GIA @topic:1


Title: Visit Europe’s First Diamond Mine Abstract: If variety is the spice of life, you’ll appreciate our Summer 2017 issue. We offer six diverse articles featuring Russia’s Lomonosov diamond mine, carbonado, photoluminescence (PL) mapping, Vietnamese tourmaline, nephrite color determination, and Montana sapphire. In addition, we provide a full-color wall chart of characteristic sapphire inclusions.

Photoluminescence mapping shows great promise for detecting sophisticated diamond color treatments.

In August 2016, GIA’s Dr. Karen Smit and Russell Shor were fortunate enough to visit Russia’s Lomonosov diamond mine. This deposit is located about 60 miles (100 km) north of the historic port of Arkhangelsk, at a northerly latitude much like Canada’s Diavik mine. In our lead article, they share insight into its geology, operations, and diamond production. Rooted in younger Proterozoic rocks—similar to Australia’s off-craton Argyle lamproite pipe— Lomonosov’s two kimberlite pipes produce a high proportion of small gem-quality diamonds, including a tiny amount of highly valuable fancy colors, including pink. Named for its resemblance to charcoal, carbonado is one of the most intriguing diamond forms. In our second paper, Prof. Stephen Haggerty of Florida International University reviews his findings from a study of hundreds of examples from the only known sources: Brazil and the Central African Republic. He evaluates origin theories, including terrestrial and extraterrestrial models.

High-speed PL mapping can plot the distribution of optical centers in diamond. In his study, GIA research associate Lorne Loudin examines an unusual irradiated HPHT synthetic diamond of mixed type. He demonstrates a clear correlation between concentration of optical centers and diamond growth sectors, confirming that the technique shows great promise for detecting sophisticated diamond color treatments.

Luc Yen tourmaline is the subject of our next paper, from Nguy Tuyet Nhung of the Gemmological Center of the Vietnam Gemstone Association and a team of researchers. They survey the gem’s distribution in the area, its geology, and suitability for use as gems, carvings, or mineral specimens.

In our fifth paper, Xiaoyan Feng, senior engineer at NGTC in Beijing, and her research team use Raman spectroscopy to investigate and define color boundaries in nephrite from China and Taiwan.

Following the Winter 2016 emerald wallchart, we present the next in the series, which features some characteristic internal features of natural, treated, and synthetic sapphire. The chart is from the same team of inclusion specialists, led by GIA’s Nathan Renfro and John Koivula.

In our final article, Tao Hsu and her coauthors survey alluvial sapphire production in the U.S. state of Montana. They note the prevalence of small-scale mining and the importance of gem tourism, but indicate that larger, mechanized operations are expanding production at these sources.

Our Lab Notes section offers entries on melee-size CVD synthetics in parcels and jewelry, CVD synthetic overgrowth on natural diamond, and non-nacreous “rosebud” conch pearls. Topics in our Micro-World section include kyanite in diamond and molybdenite “phantoms” in quartz, while GNI features new gem finds such as Ethiopian sapphires and common opal from Mexico.

Please enjoy the Summer edition! Source: GIA @topic:4


Title: Carnegie Research: Every Diamond Tells a Story Abstract: The work of Carnegie scientist, Dr. Steven Shirey and his co-workers has pushed the age of some diamonds back as far as 3.5 billion years. Duncan Pay © GIA, courtesy Carnegie Institution of Washington

                      To Dr. Steven Shirey, a senior scientist at the Carnegie Institution of Washington, every diamond tells a compelling story.

One of Shirey’s objectives, as a research scientist, is to get word out about his work into the nature of diamond and its fascinating origins deep beneath our planet’s surface. Diamonds, for Shirey and his co-workers, are unique containers that preserve minerals from deep within the earth. These tiny samples—forged under almost unimaginable pressures and temperatures— make it possible for scientists to peer hundreds of kilometers deep into the earth’s mantle.

At GIA, we also want to tell the geologic story of diamond because it underscores the unique value of the gem as a “special stone.” Shirey’s objectives are complimentary to ours: he knows his research into the age of diamond—and what it tells us about earth history—provides powerful tools for savvy jewelry salespeople to pique a customer’s interest in the gem.

Objectives

We really wanted to set up an ongoing relationship between GIA and the Carnegie Institution so this fascinating topic would be updated in our courses and website to benefit students and the public. The plus for Shirey, and his colleagues at Carnegie, is that we can expose their work to a different, more gem-focused audience.

We approached Shirey to write an article for Gems & Gemology on the knowledge available about diamond’s origin that we published in the Winter 2013 issue. As part of this initiative, a GIA team traveled to Shirey’s home institution, the Department of Terrestrial Magnetism in mid-2013.

We also wanted to document his work on inclusion dating of diamond, which has pushed the age of some diamonds from Canada back as far as 3.5 billion years. The concept that a tiny inclusion captured in a diamond crystal might provide an age of this magnitude—three quarters the earth’s age—is mindboggling.

The implication is that these minerals—passengers in the fabric of the diamond—have lain undisturbed for up to 3.5 billion years and might represent conditions when the earth’s geological processes were very different from today’s.

	These tiny diamond crystals contain sulfide mineral inclusions, which Shirey and his coworkers can use to determine their ages. Pedro Padua © GIA, courtesy Carnegie Institute of Washington
“I want to go back in earth’s history to see if the pattern of diamond growth tells us anything unique about the evolution of earth as a planet,” Shirey says.

His research involves selecting suitable inclusion-bearing diamonds from working mines, slicing them into sections to examine their growth history, and finally, breaking out the inclusions within them for age-dating studies.

“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 chuckle.

Other Diamond-related Research at Carnegie

We also wanted to provide a snapshot of Carnegie’s other diamond-related research. Two of the Carnegie Institution’s six research departments are based at the same Washington campus: the Department of Terrestrial Magnetism (DTM) and the Geophysical Laboratory.

The DTM was founded in 1904 to map the earth’s geomagnetic field as part of an emphasis on understanding the earth and our planet’s place in the universe. Today, it houses an interdisciplinary team of planetary scientists: astronomers, astrophysicists, geophysicists, and geochemists. They’re discovering planets outside our solar system, determining the age and structure of the universe, and studying the causes of earthquakes and volcanoes. Shirey’s diamond work is a subset of this research, one that illuminates our planet’s depths.

Shirey’s colleague, Dr. Jianhua Wang—a senior research scientist in the same department—investigates the growth structures of diamonds and the sources of the carbon and nitrogen within them. His work—using the Institution’s sophisticated ion microprobe—is able to separate diamonds that crystallized from carbon originally at the earth’s surface, from those that formed from ‘primordial’ carbon that originated deep in the mantle.

“This technique can show you where the carbon in a diamond came from,” Wang  says. “Whether it’s from the top—the surface of the earth—or it’s of deep mantle origin.”

	Dr. Wang explains the growth structure of a diamond using this cathodoluminescence (CL) image, which reveals its many layers. Dr. Wang’s work on carbon and nitrogen isotopes reveals much about how, and from which carbon sources diamonds grow. Duncan Pay © GIA, courtesy Carnegie Institution of Washington
Just next door, the Geophysical Laboratory—founded a year later, in 1905—examines the physics and chemistry of Earth’s interior. The lab is a world leader in petrology and high-pressure/ high-temperature (HPHT) physics, including the growth of chemical vapor deposition (CVD) synthetic diamond.

Valerie Hillgren, a research scientist there, uses HPHT presses not to grow diamonds, but to mimic, on a small scale, the formation of planets. She’s most interested in the separation of a planet’s core from its mantle, and is studying Mercury. “What we’re looking at is how the chemistry of different elements is partitioned between the mantle and the core of a planet, and how that happens under higher pressure,” she says.

	Videographer Pedro Padua records the closure of a high-pressure press at the Carbegie Institution's Geophysical Laboratory. Duncan Pay © GIA, courtesy Carngie Institution of Washington
Between them, these two departments have been responsible for a wide range of important discoveries, including mapping the earth’s magnetic field, the first fission of the uranium atom, the concept of “dark matter,” and in the early 1950s, the determination of the age of the earth to within about 2 million years. Before then, the earth’s age was ‘in ambiguo’—Latin for ‘in doubt’—and the margin of error was up to 2 billion years. Carnegie researchers put the age of the earth  on a sound footing. Today’s research encompasses all aspects of formation of the earth and solar system by looking at meteorites and radioactive decay systems for dating rocks and minerals.

Our aim at GIA is to stay in touch with Carnegie’s diamond-related research and publish regular updates and contributions on the GIA website and in Gems & Gemology. Source: GIA @topic:7


Title: Why Didn't That 1,109 Carat Diamond Sell? Abstract: The 1,109 ct Lesedi La Rona diamond is the second largest gem quality diamond ever discovered, but it did not meet its reserve price at the June 29 auction at Sotheby’s London. Courtesy Lucara Diamond Corp.

	The failure of the second largest gem quality diamond ever discovered to find a buyer at a well-publicized public auction touched off a great deal of speculation this month. Lucara Diamond Corp. mined the 1,109 carat (ct) diamond in Botswana last year and named it Lesedi La Rona (“Our Light” in the Tswana language). It went up for sale at Sotheby’s London on June 29 and the price was expected to be “in excess of $70 million” − but the high bid of $61 million did not meet the reserve.

	It was one of the only rough diamonds ever offered at a public sale. The CEO of Lucara, William Lamb, in a pre-sale interview with the Antwerp newsletter “Diamond Loupe,” explained why the company took this unusual step:

	“The Lesedi is estimated at 2.5 to 3 billion years old, which means that the crystal must have started growing very early on during the creation of the Earth. You cannot replicate it by any means, not by synthetic manufacturing or anything else. It will never be exactly the same. It won’t have the same inclusions, it won’t have a little gap somewhere, it won’t have this growth plane and it won’t be that large. People simply do not understand how long it takes to grow a stone, especially one of this size, or anything that is going to be polished into 100 carats for that matter.”

	Lucara sold an 813 ct rough diamond, found late last year, for $63 million at its private auction reserved for company clients several weeks before, but the timing for the Sotheby’s sale could not have been worse.

	The Sotheby’s auction occurred just six days after Britain’s Brexit vote roiled the world currency and equity markets. The sale, conducted in U.S. dollars that increased sharply in value after the vote, meant buyers paying in other currencies would pay a premium. (Even the Chinese Yuan declined a few percentage points against the dollar).

	In addition, based on Sotheby’s video of the diamond and from comments by a dealer who had inspected it, possible internal fissures could have limited its yield; the 813 ct stone was much cleaner.

	Finally, it’s certain that a number of key rough dealers had no intention of bidding for the stone: Sotheby’s 12% buyer’s premium would have added $8.4 million to a winning bid at the probable reserve of $70 million.

	That reluctance was evident in the room. Auctioneer David Bennett opened the bidding at $50 million − and there was no rush to top it. The price advanced very slowly before stalling at $61 million.

	Other than this diamond, prices have remained quite strong for very large colorless diamonds and top fancy colors, as the results of this auction season attest.

	Since the unsuccessful auction,  The Economist , Forbes and several newspapers have used the Lesedi La Rona as an example of how the diamond business is facing difficulties from reluctant millennials and competition from synthetics.

The Economist cited a Frost & Sullivan study claiming that softening diamond prices and rising costs will cut world diamond production to less than 15 million carats within 30 years (compared to 130-plus million this year), while production of synthetic diamonds will rise to 60 million carats in that time.

	Forbes, working from a Morgan Stanley commodities report, said synthetics would be increasingly disruptive for the diamond market, especially for smaller diamonds under 0.2 carats, which are easier for manufacturers of these stones to produce.

	The report also noted that mine production of natural diamonds is on the rise again (predicting a 9% increase to 143 million carats in 2016), but that sales remain nearly stagnant, causing inventories of both rough and polished to swell again.

	ABN AMRO bank, one of the industry’s leading lenders, warned that rising inventories may lead to softening diamond prices once again. The bank said some of the improvement in the rough market has been driven by dealers who believe prices will increase as consumer demand rises. Their actions, according to the bank, however, have bloated inventories to levels that are not sustainable because retail sales have not increased as expected, thus jeopardizing the fragile recovery.

	As expected, De Beers backed away from its aggressive selling posture of the first half of the year and sold $540 million at its June 20-24 sight, now called cycle. The fact that there were few goods left on the table was taken as a sign that the company and other major producers (Alrosa, Rio Tinto) have struck a realistic balance between price, demand and supply. The July 25-29 cycle likely will stay on the conservative side. Source: GIA @topic:8


Title: Diamond Cut: Anatomy of a Round Brilliant Abstract: This graphic illustrates the measured and visually assessed proportions that affect a round brilliant diamond’s cut grade.

	A specific set of terms is used to describe parts of a polished diamond. Each part of a diamond makes its own contribution to the diamond’s appearance.

	In the standard round brilliant, there are 57 or 58 facets. The table facet, usually the largest facet on the diamond, helps gather light from above and either reflects it back to the observer or directs it into the diamond’s interior. The crown facets, consisting of 8 bezels, 8 stars, and 16 upper halves, gather and disperse light to create brightness, fire, and a scintillating pattern of light and dark. The pavilion facets, consisting of 16 lower halves, 8 mains, and an optional culet, reflect the light back through the crown to the viewer’s eye. All of these facets work together creating each diamond’s unique appearance.

Average Girdle Diameter

	The diameter of a round diamond is the distance from one girdle edge to the opposite girdle edge, straight through the center.

	Because even well-cut round diamonds are never perfectly round, the diameter is measured in several places, recording the minimum (smallest) and maximum (largest) measurements.

	The average girdle diameter is a calculated value obtained by the following formula, which is then reported to the nearest hundredth of a millimeter (0.01 mm):

	Average girdle diameter = (minimum diameter + maximum diameter) ÷ 2

	This proportion is used in calculating certain percentages such as table size, total depth, crown height, and pavilion depth.

	Total Depth Percentage

	The total depth percentage of a round brilliant diamond is the table-to-culet depth, expressed as a percentage of the average girdle diameter and reported to the nearest tenth of a percent (0.1%).

	The total depth percentage is a calculated value obtained by the following formula:

	Total depth % = (depth ÷ average girdle diameter) x 100

Table Percentage

	The table percentage of a round brilliant diamond is the average of four table measurements (from bezel point to bezel point) expressed as a percentage of the average girdle diameter. It is reported to the nearest whole percent (1%).

	The table percentage is a calculated value obtained by the following formula:

	Table % = (average table size ÷ average girdle diameter) x 100

	Table size can have a significant impact on the diamond’s face-up appearance, especially when it’s paired with certain combinations of crown and pavilion angles.

Star Length Percentage

	Star length percentage is the length of the star facet expressed as a percentage of the girdle-to-table distance. The average of the eight star length percentages is reported to the nearest five percent (5%).

	Star facets that are very short or very long can have a negative effect on a diamond’s face-up appearance.

Crown Angle

	Crown angle is the measured angle between the bezel facet plane and the table plane. The average of eight crown angle measurements is reported to the nearest half of a degree (0.5°).

	Crown angle can significantly affect a diamond’s face-up appearance. Generally, crown angles from 32 to 36 degrees produce attractive, bright, and fiery diamonds if combined with the right table percentage and pavilion angle.

Crown Height Percentage

	Crown height percentage is the diamond’s crown height, measured from the table to the intersection of the bezel facet and the girdle, expressed as a percentage of its average girdle diameter. It is reported to the nearest half of a percent (0.5%).

	Crown height percentage is a calculated value obtained by the following formula:

	Crown height % = (average crown height ÷ average girdle diameter) x 100

Pavilion Angle

	Pavilion angle is the measured angle between the pavilion main facet plane and the table plane. The average of eight pavilion angle measurements is reported to the nearest 0.2 degrees.

	Subtle pavilion angle differences can have a significant impact on the diamond’s face-up appearance. For instance, steep pavilion angles can produce dark areas under the diamond’s table.

Pavilion Depth Percentage

	Pavilion depth percentage is the diamond’s pavilion depth, measured from the culet to the intersection of the pavilion main facet and the girdle, expressed as a percentage of its average girdle diameter. It is reported to the nearest half of a percent (0.5%).

	The average pavilion depth percentage is a calculated value obtained by the following formula:

	Pavilion depth % = (average pavilion depth ÷ average girdle diameter) x 100

Lower-Half Length Percentage

	Lower-half length percentage is the length of a pair of lower-half facets expressed as a percentage of the girdle-to-culet distance. The average of eight lower-half length percentages is reported to the nearest five percent (5%).

	Lower-half facets that are very short or very long can have a negative effect on a diamond’s face-up appearance, especially its pattern.

Girdle Thickness Percentage

	Girdle thickness percentage is the average thickness of a diamond’s girdle, measured at the eight bezel/main “hill” positions, and expressed as a percentage of average girdle diameter. Hill positions are the “thick places” located where the bezel and main facets meet. It is reported to the nearest half of a percent (0.5%).

Girdle Thickness Description

	Girdle thickness is visually assessed at the "valley" positions, as a range between the thinnest (minimum) and the thickest (maximum) areas. Valley positions are the "thin places" located between the bezel/main intersection and where the upper and lower halves meet.

	Descriptions of girdle thickness include extremely thin, very thin, thin, medium, slightly thick, thick, very thick, and extremely thick.

	Thinner girdles can affect the diamond’s durability, whereas thicker girdles can hide unnecessary weight. The cut grade can be lowered in both of these cases.

Brillianteering or Girdle Thickness Variation

	When the angles and positions between the upper- and lower-half facets are normal in relation to the bezel and main facets, the facet junctions are distinct and the girdle is evenly scalloped.

	This illustration shows a normal girdle.

Painting
Painting refers to the tilting of the upper- or lower-half facets toward the bezel or main, resulting in thinner “hill” positions where the bezel and main facets meet. The angle of the upper- or lower-half facets is reduced, becoming close to the angle of the bezels or mains, and blurring the visual distinction between them.

	The top illustration shows painting on the crown. The bottom illustration shows painting on the pavilion.

Digging Out
Digging out is the opposite of painting. The upper- or lower-half facets, or both, are tilted away from the bezel or pavilion facets and toward each other, resulting in thinner “hill” positions where upper- and lower-half facets meet. The angle of the upper- or lower-half facets is increased, and the junction between the half facets becomes visually indistinct.

	The top illustration shows the crown with digging out. The bottom illustration shows the pavilion with digging out.

	Painting and digging out can occur on a diamond’s crown, pavilion, or both. Both painting and digging out are used to retain weight, and can have an impact on a diamond’s brightness and pattern. As these features become more severe, so do their impact on the cut grade.

Culet Size Description

	Culet size is described as the width of the culet facet, when present, relative to a round diamond’s average girdle diameter. Descriptions include none, very small, small, medium, slightly large, large, very large, and extremely large.

	"None" is used when there is no culet facet, which is sometimes referred to by the trade as a “pointed” culet.

	Larger culets can have a negative effect on the diamond’s face-up appearance, specifically affecting its pattern, and lowering its cut grade. Source: GIA @topic:4


Title: Major Diamond Find Brightens Market Abstract: The 1,111 ct. rough found by Lucara Mining in the Kerowe Mine in Botswana is only the second time in history that a diamond weighing more than 1,000 carats has been found. The company plans to auction the diamond next year. Photo courtesy Lucara Mining

The news from Lucara Mining, which found three huge diamonds – 1,111, 813 and 374 carats − all in the same week from the company’s Kerowe Mine in Botswana, brightened an otherwise lackluster diamond market.

Two of the diamonds are the second and sixth largest ever found.

All three will be sold in Antwerp early next year, according to Lucara. Given the enormous wealth some buyers are putting into major diamonds and colored gems, the buyer of the 1,111 carat (ct.) rough will likely go for the maximum final cut size, striving to exceed the 530 ct. Cullinan I, the world’s largest colorless diamond that is a centerpiece of the British Crown Jewels, and the 545 ct. Golden Jubilee, a yellowish brown diamond in the Crown Jewels of Thailand. The final cut, of course, will depend upon whether the inclusions and fissures within the stone will permit such a large stone.

The enormous wealth being spent on top diamonds was evident at recent Sotheby’s and Christie’s auctions. As reported around the world, a Hong Kong businessman, Joseph Lau, paid a world record of $48 million for a 12.08 ct. Fancy Vivid blue diamond – at $4 million per carat, it was also the record per-carat price ever paid for a gemstone. The day before, he paid $28.5 million for 16.08 ct. Fancy Vivid pink diamond.

	The $48 million Blue Moon Josephine, a 12.08 ct.  Fancy Vivid blue, has become the most expensive gemstone ever sold at auction. Its $4 million per carat price exceeded the previous record by $1 million. Photo courtesy Sotheby’s
Lau named both diamonds, which were graded by GIA, after his daughter, Josephine. Last year, he paid a record-breaking $32.6 million for a 9.75 ct. Fanvy Vivid blue diamond and named it Zoe after his other daughter.

In the more commercial side of the diamond market, major diamond producers have trimmed rough sales way back as the industry continues to grapple with high inventories, diminished credit and stagnant demand.

De Beers’ Dec. 7-11 sight is expected to be a repeat of November’s $70 million allocation – the smallest since the world financial crisis in the fall 2008. De Beers has reportedly returned to deferring purchases from its own mining partners, in particular Debswana, a practice it has not done in 20 years, when Russian diamonds were flooding the market and depressing prices for smaller stones.

Alrosa, the agency that mines and sells Russia’s diamonds and Rio Tinto, which owns Argyle Diamond Mine in Australia and a majority share of Diavik in Canada, have instituted provisions that allows their clients to defer purchases.

Alrosa rough diamond sales volume fell 42% short of its plan for the third quarter of the year, according to a company statement. The decline was especially steep in September, when the company not only slashed prices 8%, but also allowed its clients to defer up to 50% of their purchases. The company, which held its prices in October, had forecast $5 billion in revenues for the year, but analysts believe actual sales will come in about $3.6 billion.

The company’s diamond production totaled 23 million carats through the third quarter, down 5.8 million carats from the same period of 2014. But revenues-per-carat sales were 3.5% higher, indicating that Alrosa was concentrating its sales into larger goods and stockpiling the smaller goods.

	The 16 ct. Fancy Vivid Pink diamond sold for $28.5 million to the same buyer who bought the record-breaking blue diamond. Photo courtesy Christie’s

	Retail
Jewelry demand in the U.S. is growing, though slowly this year. According to U.S. Department of Commerce data, sales of fine jewelry increased 4.8% in September, over the same month last year. Much of that increase went to online sellers, which include brick and mortar retailers who have an e-commerce division.

Retail analysts are expecting jewelers to discount heavily during holiday sales, even as they predict a respectable season. Price cutting began early with one major department store, Macy’s, advertising 30% off on engagement rings during the holiday season.

Blue Nile, the leading online diamond seller, has scaled back its sales growth estimates for 2015, expecting its yearly sales to total between $488 and $498 million, instead of the originally forecast $505 million. Last year’s total sales were $473.5 million. The company is basing its new forecast on a third quarter sales increase of 4%.

Worldwide, demand from luxury watches plunged 12% in all major markets in October, compared to the same month last year. The Federation of the Swiss Watch Industry reported: sales to Hong Kong fell 39% to $258 million; exports to the U.S. declined 12% to $232 million; and orders from China declined 5% to $120 million. Exports to other European countries were down by 4% to 5%. Source: GIA @topic:8


Title: Visit to the China Diamond Exchange Center Abstract: Shanghai, one of the world’s financial capitals, is home to the China Diamond Exchange Center. Photo courtesy of China Diamond Exchange Center.

                      In July 2013, a GIA team visited the China Diamond Exchange Center in Shanghai during an extensive trip undertaken to document China’s gem and jewelry industry. The trip was arranged by Dr. Tao Hsu, technical editor for Gems & Gemology, and the Exchange was an important part of the itinerary.

	The Diamond Exchange in Shanghai is home to dealers, government agencies, a lab,
	and shipping services. It is the central location for all of China's diamond imports and
	exports. Photo courtesy of China Diamond Exchange Center.
The China Diamond Exchange Center is home to the Shanghai Diamond Exchange (also known as the Diamond Exchange). Before it was established in October 2000, taxation—including import tariff, value added tax (VAT), and sales tax on imported diamond—was around 35 to 40 percent. Diamond taxation policy is now very favorable in China, with a VAT of only 4 percent. (In reality, all goods imported into China are charged 17 percent VAT, but 13 percent is refunded for diamonds, leaving the net VAT charge on diamond at 4 percent.) This lowered taxation came about due to input from the Diamond Exchange, and it was instrumental in greatly reducing the quantity of diamonds smuggled into the country to avoid the higher taxes.

	The Shanghai Diamond Exchange was established in October 2000. Photo courtesy of China Diamond Exchange Center. .

	The Exchange’s Influence
The Chinese diamond industry benefited greatly from the formation of the Diamond Exchange. Before it was established, official annual diamond import value was about US$1 million. By 2011, import value had reached over US$5 billion, of which $2 billion was imported solely into mainland China. While imports dropped by 10 percent in 2012 due to worldwide economic conditions, indications for 2013 are that the import figure will be higher.

The Diamond Exchange joined the World Federation of Diamond Bourses in 2004, and hosted the 33rd World Diamond Conference in Shanghai in 2008.

	The 33rd World Diamond Conference was held at the Diamond Exchange in 2008. Photo courtesy of China Diamond Exchange Center.

	The Mission of the Exchange
The Diamond Exchange is China's only legal location for diamond import and export. Set up by the central government, its mission is to make trade more convenient by simplifying diamond import and export procedures.

According to Chinese law, all imported diamonds must go through the Exchange and several procedures must be followed. One of those is that diamonds imported into China must be declared and sealed in customs, or they are considered illegally smuggled. The diamonds are unsealed, inspected, and assessed by an expert at the Exchange before taxation is imposed.

	All diamonds entering China, both rough and cut, must come through the China
	Diamond Exchange. Photo courtesy of China Diamond Exchange Center.

	Kimberley Process Certificates
Kimberley Process certificates must accompany rough diamonds. Their mandatory inspection is strictly carried out in China. A special department in the Diamond Exchange  is set up for inspecting and registering Kimberley Process certificates. Once the certificates pass inspection, the rough can be sold in the domestic market. China was elected as the Deputy Chairman Country of the Kimberley Process in 2013. In 2014 China became the Chairman Country and one officer of the National Bureau of Quality Inspection will took the Chairman position.

	Kimberley Process certificates for rough diamond are inspected and registered in a specialized department of the Diamond Exchange. Photo courtesy of China Diamond Exchange Center.

	Open Platform
The China Diamond Exchange Center is a totally open platform that welcomes diamond dealers from all over the world. It has more than 350 members, among which 67 percent are overseas members from Israel, Belgium, Great Britain, France, the United States, Japan, Africa, and other countries. There are 114 member diamond companies from mainland China, 62 from Hong Kong, 50 from India, 32 from Israel, 23 from Belgium, and the rest from other countries.

	The China Diamond Exchange is one of the world’s leading diamond exchanges and attracts industry leaders from all over. Photo courtesy of China Diamond Exchange Center.

	Membership Requirements
A diamond company that wants to be a member of the China Diamond Exchange has to meet certain requirements. The first requirement is that the company must have been engaged in the industry for at least three years and must be familiar with its operation. Secondly, the company must be introduced by two registered members of the China Diamond Exchange. A new member has to go through a one-year probationary period.

The third is a financial requirement: a mandatory US$20,000 one-time admission fee. The fee is refundable if a member wants to withdraw from the Exchange as a result of unsuccessful business endeavors or some other reason.

Another important condition is that a diamond company operating in China must be approved by the Diamond Administration of China (DAC) and registered according to Chinese law. After approval and licensing by the DAC, a company is allowed to engage in import and export business and take part in customs, tax administration, and Kimberley Process procedures.

	Diamond-trading information from the China Diamond Exchange attracts many dealers who want to do business in this fast-growing market. Photo courtesy of China Diamond Exchange Center.

	Main Functions of the DAC
The DAC and other government organizations jointly control everyday diamond imports and exports across the country as well as trade within the China Diamond Exchange.

The main functions of the DAC are administration and statistical analysis of national diamond imports and exports under normal trade conditions; examination and verification of transactions under rules of the Diamond Exchange, as well as supervision of the Exchange’s operations; and  coordination with other government officials inside the Exchange regarding issue relating to the diamond trade. The DAC also conducts examination and approval of the establishment of foreign-invested diamond companies, and daily regulation of their operations. It participates in the formulation of regulations and policies concerning diamond import and export and other diamond transactions, and provides  services to the Exchange and to domestic and foreign diamond companies.

	Building and Departments
The tower that houses the China Diamond Exchange Center is an impressive structure in Shanghai that covers an area of 49,000 square meters. The building is designed to be a one-stop shop for the diamond trade and boasts the latest in security, communications, and technology. The DAC is located in the tower, along with other diamond-related government organizations.

	The Diamond Exchange is a one-stop shop for all diamond trading needs, from taxation requirements to shipping. Photo courtesy of China Diamond Exchange Center.
Supporting businesses include banking, a grading lab, shipping companies, training organizations, diamond associations, and security escorts.

Customs
Customs is in charge of handling the declaration of diamond import and export, the checking of diamonds passing through the Exchange, the collection of diamond import tax, supervision of the trade and storage of diamonds inside the Exchange, and checking of diamonds going out of the Exchange for processing.

Inspection and Quarantine Administration
The Inspection and Quarantine Administration is responsible for Kimberley Certificate verification and issuance. It also checks rough import and export under normal trade in China and under subcontracted trade in Shanghai.

The Taxation Office
The Taxation Office is in charge of the administration of taxes for Exchange members’ domestic trade. The Pudong branch of the taxation office is in charge of handling VAT for member enterprises.

The Industrial and Commercial Office and Foreign Exchange Office
The Industrial and Commercial Office is in charge of diamond-related industrial and commercial administration, while the Foreign Exchange Office is in charge of diamond-related foreign exchange administration.

	Government departments within the Diamond Exchange handle all the legal aspects of dealing in diamonds in China. Photo courtesy of China Diamond Exchange Center.

	China Diamond Industry Development
Diamond jewelry entered the mainstream Chinese market in the 1980s. Along with rapid economic and social development, the continual improvement of people’s living standards, and the fast rise of consumerism, diamond jewelry sales have been increasing at a rate of 15 to 20 percent a year. China is now the world’s second largest consumer market for diamonds, overtaking Japan.

China’s diamond-polishing industry also started to grow significantly in the early 1980s, and growth became more rapid in the 1990s. Currently, China is the second largest diamond-polishing country, after India. China polishes over six million carats of diamonds annually and employs over 50,000 polishers in more than 80 medium and large factories. Most of the factories are located in Guangdong, Shandong, and Shanghai. China has developed a niche for high-quality precision cutting and marketed their product as China Cut.

	China has a thriving diamond-polishing industry. Photo courtesy of China Diamond Exchange Center.
Most of the diamond polishing in China is subcontracted work for foreign clients, who hire domestic firms to polish their diamonds. There are also numerous jewelry manufacturing firms producing diamond jewelry for export.

All of this phenomenal growth is due in part to the policies and organization of the China Diamond Exchange Center in Shanghai. Source: GIA @topic:8


Title: Natural-Color Purple Diamonds from Siberia Abstract: Twelve natural-color purple diamond crystals from Siberia, and seven round brilliants that were faceted from some of these crystals, were studied using spectroscopic methods to better understand their color and its causes. Aspects of their color and the various structural defects in these purple diamonds are due to their post-growth plastic deformation in the earth. All the samples exhibited prominent parallel planar lamellae along which the purple color was concentrated. Source: GIA @topic:4


Title: Diamonds: A Slice off the Old Rough Abstract: This colorless diamond slice, approximately 21 x 17 x 3 mm, shows an attractive pattern of inclusions. The diamond was offered for sale at the Hong Kong Watch & Jewellery Show in September. Courtesy of Dynamic International. Photo by Russell Shor.

                      Diamond inclusions can tell a unique story about a particular stone, but they invariably lower its value. There is one exception, however. Diamond cutters with an eye for nature’s art have created “diamond slices”—thinly sliced sections of large, highly included rough for jewelry designers.

The idea, say the manufacturers who create these pieces, is to cut the rough to show interesting patterns while keeping the stone’s original outline. The more interesting the inclusions and their patterns, the higher the price.

Approximately five exhibitors at the September Hong Kong Watch and Jewellery Show were featuring diamond slices.

	A grayish colored diamond slice approximately 18 x 16 x 3 mm. Courtesy of Dynamic International. Photo by Russell Shor.
Raja Malpani, president of Mumbai-based Dynamic International, said most diamond slices are prepared in India, with some Israeli production as well. Dynamic offered the largest pieces seen at the show and provided samples for these photos.

Diamond slices start as large, highly included or opaque rough. Generally the manufacturers laser-slice the rough stones into 2 or 3 mm thick slabs of irregular shape, ranging from 5 to 20 mm depending on the shape of the original rough. They apply extremely shallow “pavilion” facets to one side, polishing a flat “table” on the other. The prices can vary widely between $10 per carat for opaque pieces to $700 per carat for transparent stones with decorative inclusion patterns.

Diamond slices have been in the market for three or four years, according to Malpani. Several U.S. designers (including Gara Post of Los Angeles and Ashley Morgan of San Francisco) have included them in their collections but Malpani said they have just started selling in Asia.

The manufacturers recommend that designers bezel-set the slices because diamonds, while extremely hard, are brittle and can chip or crack fairly easily.

	A translucent yellowish diamond slice approximately 15 x 16 x 3 mm offered for sale at the September Hong Kong Watch & Jewellery Show by Dynamic International. Photo by Russell Shor. Source: GIA @topic:4


Title: Diamond, Artificially Irradiated and Coated Brown Abstract: Figure 1. The diamond with a Fancy reddish brown color (left) was revealed to be Fancy Dark orangy brown once the coating and red hue were removed (right). Photos by Jian Xin (Jae) Liao.

              Red is arguably the rarest and most valued color in diamond. It is known to bring record-breaking prices at auction, as in the case of the 0.95 ct Hancock Red, which sold for nearly $1 million per carat in 1987. Some will go to great lengths to achieve this color, even resorting to unusual multiple treatments.

The New York laboratory recently examined a Fancy reddish brown 0.28 ct round brilliant diamond submitted for color origin identification (figure 1). Spectroscopic analysis immediately revealed that it had been artificially irradiated to create the reddish brown color. The presence of an amber center, identified by infrared spectra, indicated that this diamond was likely brown prior to treatment. Further investigation using the DiamondView determined that the stone’s pavilion facets had also been coated, a feature not apparent with microscopic observation. DiamondView images displayed weak luminescence, with more intense luminescence concentrated at facet edges, junctions, and where the stone had been scratched. Boiling removed the coating, eradicating the red component and changing the color grade to Fancy Dark orangy brown. Removing the coating also produced a much more luminescent DiamondView image (figure 2).

Figure 2. DiamondView images of the diamond with the coating (top row) and after the coating’s removal (bottom row). The dark spots in the bottom left image are remnants of the coating substance. Images by Paul Johnson.
This stone indicates an attempt to induce red color in diamond, presumably to increase the value. Although this effort proved unsuccessful, it emphasizes the need for vigilance when analyzing diamonds with rare color. Their appeal, and the number of treatment techniques to create these colors, is sure to grow. Source: GIA @topic:4


Title: CVD Synthetic Diamonds from Gemesis Corp. Abstract: Gemological and spectroscopic properties of CVD synthetic diamonds from Gemesis Corp. were examined. Their color (colorless, near-colorless, and faint, ranging from F to L) and clarity (typically VVS) grades were comparable to those of top natural diamonds, and their average weight was nearly 0.5 ct. Absorption spectra in the mid- and near-infrared regions were free from defect-related features, except for very weak absorption attributed to isolated nitrogen, but all samples were classified as type IIa. Varying intensities of [Si-V]- and isolated nitrogen were detected with UV-Vis-NIR absorption spectroscopy. Electron paramagnetic resonance was used to quantify the neutral single substitutional nitrogen content. Photoluminescence spectra were dominated by N-V centers, [Si-V]-, H3, and many unassigned weak emissions. The combination of optical centers strongly suggests that post-growth treatments were applied to improve color and transparency. PL spectroscopy at low temperature and UV fluorescence imaging are critical in separating these synthetic products from their natural counterparts. Source: GIA @topic:4


Title: Coated Pink Diamond — A Cautionary Tale Abstract: The Diamond Trading Company (DTC) Research Centre had the opportunity to examine a diamond that, on submission to a commercial gem laboratory, was stated to have been HPHT treated. However, spectroscopic analysis yielded data inconsistent with this statement. After further testing, it was determined that this diamond, which originally was probably pale yellow, had been coated to change its color to the equivalent of Fancy Intense purple-pink. Careful examination with a microscope revealed evidence of a coating exclusively on the pavilion facets. Elemental analysis of the coating suggests it may be calcium fluoride with a gold impurity that was added either to generate the absorption responsible for the pink color or to assist as a nucleating agent for the calcium fluoride film. Source: GIA @topic:4


Title: A Gemological Study of a Collection of Chameleon Diamonds Abstract: Chameleon diamonds are among the rarest of gem diamonds. This article reports on a unique collection of 39 chameleon diamonds ranging from 0.29 to 1.93 ct, which exhibited temporary changes in color when heated to approximately 150°C and, for some, after prolonged storage in the dark (i.e., thermochromic and photochromic color changes, respectively). Most changed from “olive” green to brownish yellow or yellow, although some changed from light yellow to a more intense greenish yellow. The thermochromic and photochromic color change observed in the “olive” green chameleon diamonds is typical of “Classic” chameleons, whereas the solely thermochromic change shown by the light yellow group was the “Reverse” of that seen in Classic chameleon diamonds. The Classic and Reverse groups showed different spectroscopic and UV fluorescence characteristics, but all stones exhibited strong long-lasting phosphorescence after shortwave UV excitation. Hydrogen was identified in all samples by FTIR spectroscopy, and minor Ni-related emissions were detected by photoluminescence spectroscopy in most. Using this combination of reaction to UV radiation and spectroscopic properties, a gemologist can separate chameleon from other green diamonds without unnecessary exposure to heat. Source: GIA @topic:4


Title: An Economic Review of the Past Decade in Diamonds Abstract: The diamond industry was buffeted by extreme price volatility during the last decade, unlike any encountered since the Great Depression of the 1930s. Although the industry is currently enjoying a resurgence of activity worldwide, particularly in the Far East, today's market differs significantly from what it was 10 years ago. This article reviews the factors that led to the enormous demand for diamonds in the late 1970s, examines the causes of recession in the early 1980s, and provides an analysis of the comeback of diamond in 1986. Inasmuch as events during this period ushered many changes into the diamond trade, an understanding of how economic forces affect the supply, demand, and value of diamond is critical to all gemologists. Factors such as inflation, recession, interest rates, and disposable income, as well as fluctuations in worldwide exchange rates, had, and undoubtedly will continue to have, an impact on the health of the diamond market. Source: GIA @topic:8


Title: Pitfalls in Color Grading Diamonds by Machine Abstract: Diamonds are normally color graded by comparison with sets of master stones. This method is purely subjective and requires considerable experience. In principle, spectroscopic techniques should enable color grading with high precision by relatively inexperienced operators. In practice, there are at least two major sources of error - luminescence and scattered light - that may make spectroscopically determined color grades unreliable. Source: GIA @topic:4


Title: A Simple Approach to Detecting Diamond Simulants Abstract: This article offers a step-by-step approach to the identification of the most problematic diamond simulants. The optical and physical properties of diamond are contrasted to those of colorless strontium titanate, synthetic cubic zirconia, gadolinium gallium garnet, and yttrium aluminum garnet. If the testing methods discussed in this article are used, none of the above materials should be mistaken for diamond. Source: GIA @topic:4


Title: Synthetic Moissanite: A New Diamond Substitute Abstract: A new diamond imitation, synthetic moissanite (silicon carbide), is now being produced by C3 Inc. in near-colorless form for jewelry purposes. With refractive indices of 2.648 and 2.691, a dispersion of 0.104, a hardness of 9¼ on the Mohs scale, and a specific gravity of 3.22, synthetic moissanite is much closer to diamond in overall appearance and heft than any previous diamond imitation. The thermal properties of synthetic moissanite are also so close to those of diamond that the thermal probes currently on the market react to synthetic moissanite as if it were “diamond.” This new material can be readily separated from diamond on the basis of its anisotropic optical character, which produces a doubling in the appearance of facet junctions. A new instrument manufactured by C3 Inc. solely to distinguish synthetic moissanite from diamond was also examined for this study. Source: GIA @topic:4


Title: A Chart for the Separation of Natural and Synthetic Diamonds Abstract: A chart is provided that describes those gemological properties that are key to the separation of gem-quality yellow, blue, and near-colorless (to colorless) natural diamonds from synthetic diamonds. This format was designed to give jewelers and gemologists a ready reference to identify synthetic diamonds as they enter the jewelry trade. Magnification and luminescence are the most important testing techniques currently available to jewelers and gemologists. The most distinctive features of synthetic diamonds include color zoning, graining, metallic inclusions (often making the stone magnetic), and uneven ultraviolet fluorescence. Source: GIA @topic:4


Title: A History of Diamond Sources in Africa: Part I Abstract: For more than 100 years, Africa has produced large commercial quantities of diamonds and important individual stones. The earliest official finds were made from approximately 1867 onward, in sands and gravels of the Orange and Vaal Rivers in South Africa. Subsequently, diamonds were found in "hard rock" kimberlites and, most recently, in off-shore deposits along the western coast of South Africa and Namibia. Important discoveries have been made in many other African countries. Angola, Botswana, Central African Republic, Ghana, Namibia, and Zaire have now joined South Africa as being among the top 10 diamond-producing countries worldwide. Part I of this two-part series examines the fascinating history of these numerous discoveries in southern and central Africa from the 19th century to the present. Part II will look at eastern and western Africa, as well as the history of diamond prospecting, mining, and production on the African continent. Source: GIA @topic:7


Title: A Visual Guide to the Identification of Filled Diamonds Abstract: A microscope with various types of lighting is the most practical and reliable method to detect fracture filling in diamonds. All of the filled diamonds examined to date have shown flash effects in a variety of colors. Also seen in some stones are evidence of flow structure, trapped bubbles, incomplete filling at the surface, crackled texture, trapped bubbles, an apparent color to the filler, cloudy filled areas, and surface residue. This article is accompanied by a chart that illustrates the various features seen in filled diamonds, plus features observed in unfilled fractures with which they might be confused. Source: GIA @topic:4


Title: An Update on Filled Diamonds: Identification and Durability Abstract: The increasing numbers of fracture-filled diamonds present a major challenge to the diamond industry, especially with regard to detection and durability of the treatment in routine jewelry manufacturing and wear. This report focuses on recent products from Yehuda/Diascience, Koss & Schecter Diamonds (Genesis II), and Clarity Enhanced Diamond House (a subsidiary of Goldman Oved Diamond Co.). Like the Yehuda treatment, the latter two processes were found to be effective in improving the appearance of most of the samples examined for this study. Treated diamonds from all three firms were damaged by direct heating and by repolishing facets intersected by filled breaks. Some stones were adversely affected by some standard cleaning procedures and wear conditions. Although the lead-based glass filling materials may be detected by X-radiography and EDXRF spectroscopy, as well as by certain internal features, we found flash effects to be the most distinctive characteristic of fracture filling—observed in all the treated diamonds examined from all three firms. Source: GIA @topic:4


Title: Legal Protection for Proprietary Diamond Cuts Abstract: Despite the rapid profusion of new branded and proprietary diamond cuts in recent years, considerable confusion exists in the trade about the important differences between trademarks and patents. Proprietary brand names can be protected by trademark registration (typically noted by a registration [®] symbol next to the brand name), while proprietary designs or products can be protected by patents. Both methods have important limitations, and the recent history of cut designs reflects the importance of protecting a valuable diamond cut. A study of the proprietary designs currently in the marketplace revealed a preference for trademark protection over patents, though many designs appeared to have no patent or trademark registration. A list of recent proprietary designs is given in the Appendix. Source: GIA @topic:7


Title: A Crystallographic Analysis of the Tavernier Blue Diamond Abstract: While the Tavernier Blue has been established as the “grandparent” of the Hope diamond, the only firsthand historical documentation for it is a 17th century line drawing of questionable accuracy. It has been suggested that the diamond was crudely cut, conforming to the shape of the original crystal. If this is correct, then it should be possible to correlate the facets on the Tavernier Blue to the faces of a diamond crystal, and thus gain information on the crystallography of the original rough. This study used this information, the original drawings, and a computer model of the French Blue diamond generated from the laser scan of a recently discovered lead cast, to generate a computer model of the Tavernier Blue. This new model completely encloses the computer model of the French Blue, conforms to Tavernier’s physical description, and establishes the orientation of the finished diamond within the original diamond crystal. Source: GIA @topic:4


Title: Global Rough Diamond Production Since 1870 Abstract: Data for global annual rough diamond production (both carat weight and value) from 1870 to 2005 were compiled and analyzed. Production statistics over this period are given for 27 diamond-producing countries, 24 major diamond mines, and eight advanced projects. Historically, global production has seen numerous rises—as new mines were opened—and falls—as wars, political upheavals, and financial crises interfered with mining or drove down demand. Production from Africa (first South Africa, later joined by South-West Africa [Namibia], then West Africa and the Congo) was dominant until the middle of the 20th century. Not until the 1960s did production from non-African sources (first the Soviet Union, then Australia, and now Canada) become important. Distinctions between carat weight and value affect relative importance to a significant degree. The total global production from antiquity to 2005 is estimated to be 4.5 billion carats valued at US$300 billion, with an average value per carat of $67. For the 1870–2005 period, South Africa ranks first in value and fourth in carat weight, mainly due to its long history of production. Botswana ranks second in value and fifth in carat weight, although its history dates only from 1970. Global production for 2001–2005 is approximately 840 million carats with a total value of $55 billion, for an average value per carat of $65. For this period, USSR/Russia ranks first in weight and second in value, but Botswana is first in value and third in weight, just behind Australia. Source: GIA @topic:8


Title: Fancy Black NPD Synthetic Diamond Abstract: Figure 1. This 0.9 ct marquise proved to be a synthetic nano-polycrystalline diamond (NPD), the first one detected by a gemological laboratory. Photo by Jian Xin (Jae) Liao/GIA.

              As reported previously in Gems & Gemology, nano-polycrystalline diamond (NPD) growth technology is one of the most significant new developments in diamond synthesis (see E.A. Skalwold, “Nano-polycrystalline diamond sphere: A gemologist’s perspective,” Summer 2012 G&G, pp. 128–131). The material is completely transparent and comparable to natural diamond, while tougher than natural diamond or previous synthetic diamonds. NPD could pose a challenge to the natural diamond industry once these goods, particularly higher-quality transparent samples, enter the consumer market.

Recently, the New York laboratory tested a small, black marquise-cut stone for identification and color origin. At first glance, the 0.9 ct translucent specimen (figure 1) resembled a typical black diamond submitted to the lab for identification and color origin. One must be careful to separate such stones from synthetic moissanite. This marquise, however, revealed unusual properties strikingly similar to those of the NPD synthetic diamonds reported on by Skalwold, as well as other previously tested samples. These previously studied specimens were transparent with a yellow to brown range of color.

	Figure 2. Photomicrograph images of the heavily included synthetic diamond showed an abundance of graphite inclusions and a murky yellowish matrix. Fields of view (clockwise from top left): 1.5, 3.1, 1.5, and 4.1 mm. Photomicrographs by Paul Johnson.
Unlike natural diamond, the stone in question was heavily included with graphite crystals. The matrix hosting the inclusions had a murky yellowish color (figure 2). Using diffuse reflectance, we obtained a mid-infrared absorbance spectrum strikingly similar to that of the NPD synthetic diamonds reported in the aforementioned article. We observed the diagnostic diamond absorption peaks at approximately 2000 cm–1 and absorption in the one-phonon region, possibly due to nitrogen impurity. Peaks at approximately 3727 and 3611 cm–1 were also observed, as in the previously tested NPD samples (figure 3). Raman spectroscopy is a common and useful technique in identifying a gem diamond. Due to the nano-sizes of the crystals that compose the aggregated sample, a Raman shift is usually not detectable in NPD using visible-light laser excitations. The same feature was observed in this specimen.

	Figure 3. The mid-infrared spectrum of the synthetic NPD displayed peaks at approximately 3727 and 3611 cm–1.

	Figure 4. DiamondView images of the synthetic NPD exhibited a distinct fluorescence pattern. Images by Paul Johnson.
Further analysis using the DiamondView instrument revealed a fluorescence pattern and structure that was, again, very similar to earlier NPD samples (figure 4). Raman analysis showed a broad band at approximately 1350 cm–1 and a weak band at about 1580 cm–1; these are assigned as D- and G-bands, respectively (S. Odake et al., “Pulsed laser processing of nano-polycrystalline diamond: A comparative study with single crystal diamond,” Diamond and Related Materials, 2009, Vol. 18, pp. 877–880). Odake reported the two bands in NPD samples grown from high-purity graphite at a temperature of 2600K and a pressure of 15 GPa; both are caused by nanocrystalline graphite or amorphous carbon. Unlike Odake’s samples, which showed G- and D-bands of equal intensity, ours showed a strong D-band with a weak G-band. We measured Raman spectra at many different locations but did not observe the diamond Raman band at 1332 cm–1, an absence Odake also reported.

Testing and observations revealed the diamond to be an NPD synthetic diamond, the first detected by a gemological laboratory. Source: GIA @topic:4


Title: A Solution to Diamond Color Grading Problems Abstract: Although GIA’s system for evaluating diamond quality has been an industry benchmark since 1955, it all began with the efforts of Robert Shipley Sr. and Richard T. Liddicoat a decade earlier. This 1941 article troubleshoots the challenges of evaluating diamond color, including the need for controlled light in a standardized, consistent environment. The authors describe a prototype instrument called the Diamolite, which filters and diffuses light for consistent results, and introduce the GIA Colorimeter, a scale for measuring stone color. Source: GIA @topic:4


Title: Fancy Black NPD Synthetic Diamond Abstract: Figure 1. This 0.9 ct marquise proved to be a synthetic nano-polycrystalline diamond (NPD), the first one detected by a gemological laboratory. Photo by Jian Xin (Jae) Liao/GIA.

                      As reported previously in Gems & Gemology, nano-polycrystalline diamond (NPD) growth technology is one of the most significant new developments in diamond synthesis (see E.A. Skalwold, “Nano-polycrystalline diamond sphere: A gemologist’s perspective,” Summer 2012 G&G, pp. 128–131). The sphere’s material is completely transparent and comparable to natural diamond, while tougher than natural diamond or previous synthetic diamonds. NPD could pose a challenge to the natural diamond industry once these goods, particularly higher-quality transparent samples, enter the consumer market (E.A. Skalwold et al., "Characterization of a synthetic nano-polycrystalline diamond gemstone," Fall 2012 G&G, pp.188–192).

Recently, the New York laboratory tested a small, black marquise-cut stone for identification and color origin. At first glance, the 0.9 ct translucent specimen (figure 1) resembled a typical black diamond submitted to the lab for identification and color origin; one must be careful to separate such stones from synthetic moissanite. This marquise, however, revealed unusual properties strikingly similar to those of the NPD synthetic diamonds reported on by Skalwold, as well as other previously tested samples. These previously studied specimens were transparent with a yellow to brown range of color.

	Figure 2. Micrograph images of the heavily included synthetic diamond showed an abundance of graphite inclusions and a murky yellowish matrix. Photomicrographs by Paul Johnson/GIA, fields of view (clockwise): 1.5 mm, 3.1 mm, 1.5 mm, and 4.1 mm.
Unlike natural diamond, the stone in question was heavily included with graphite crystals. The matrix hosting the inclusions had a murky yellowish color (figure 2). Using diffuse reflectance, we obtained a mid-infrared absorbance spectrum strikingly similar to that of the NPD synthetic diamonds reported in the aforementioned article. We observed the diagnostic diamond absorption peaks at approximately 2000 cm–1 and absorption in the one-phonon region, possibly due to nitrogen impurity. Peaks at approximately 3727 and 3611 cm–1 were also observed, as in some previously tested NPD samples (figure 3). Raman spectroscopy is a common and useful technique in identifying a gem diamond. Due to the nano-sizes of the crystals that compose the aggregated sample, a Raman shift is usually not detectable in NPD using visible-light laser excitations. The same feature was observed in this specimen.

	Figure 3. The mid-infrared spectrum of the 0.9 ct black marquise-cut synthetic NPD (in red) displayed peaks at approximately 3727 and 3611 cm–1, which have been observed in some other NPD samples. The mid-IR spectrum in 2012 by Skalwold et al. (in blue) is provided for comparison.
Further analysis using the DiamondView instrument revealed a fluorescence pattern and structure that was, again, very similar to earlier NPD samples (figure 4). Raman analysis showed a broad band at approximately 1350 cm–1 and a weak band at about 1580 cm–1; these are assigned as D- and G-bands, respectively (S. Odake et al., “Pulsed laser processing of nano-polycrystalline diamond: A comparative study with single crystal diamond,” Diamond and Related Materials, 2009, Vol. 18, pp. 877–880). Odake reported the two bands in NPD samples grown from high-purity graphite at a temperature of 2600K and a pressure of 15 GPa; both are caused by nanocrystalline graphite or amorphous carbon. Unlike Odake’s samples, which showed G- and D-bands of equal intensity, ours showed a strong D-band with a weak G-band. We measured Raman spectra at many different locations, but did not observe the diamond Raman band at 1332 cm–1, an absence Odake also reported. This suggests the presence of sp2-bonded carbons instead of sp3-bonded carbons.

	Figure 4. DiamondView images of the synthetic NPD exhibited a distinct fluorescence pattern. Images by Paul Johnson/GIA.
Testing and observations revealed the diamond to be an NPD synthetic diamond, the first detected by a gemological laboratory. Source: GIA @topic:4


Title: Bright Yellow Diamonds from Sierra Leone Abstract: Figure 1. These two bright yellow diamonds (1.03 and 1.02 ct) are from alluvial deposits in the Zimmi mining area in southern Sierra Leone. In the rectangular stone, several black graphitized feather inclusions are visible. Photo by Robert Weldon.

              Diamonds referred to in the trade as “Canary yellow” are highly valued for their saturated yellow color, caused by isolated nitrogen impurities. When faceted, they can exhibit colors ranging from Fancy Intense to Fancy Vivid yellow in GIA’s colored diamond grading system. It is unusual to see a group of these rare colored diamonds from a known mining locality (figure 1).

Recently, GIA’s Carlsbad laboratory had the opportunity to examine eight faceted and five rough diamonds reportedly found in alluvial deposits in the Zimmi mining area in the Pujehun district of southern Sierra Leone. They were loaned to us for study by Israel Eliezri (Coldiam Ltd., Ramat Gan, Israel). According to Mr. Eliezri, bright yellow rough diamonds are recovered on a recurring basis from the Zimmi region.

The diamonds we examined showed highly saturated yellow colors and weighed between ~0.10 ct and just over 1.00 ct. Rough diamonds recovered from this locality are reported to occur in sizes up to about 4 ct. Under magnification, they often contain what appear to be crystalline sulfide mineral inclusions, with graphitized feathers extending outward (figure 2). Infrared spectroscopy analysis indicated that the samples ranged from pure type Ib to variable proportions of type Ib and IaA. Total nitrogen impurity concentrations varied from 8 ppm (all as type Ib) to ~340 ppm (~35 ppm type Ib, ~305 ppm type IaA). Hydrogen impurities were also detected in the samples with high total nitrogen content. Visible spectroscopy showed only gradually increasing absorption toward the violet end of the spectrum due to the isolated nitrogen.

	Figure 2. This diamond contains what is believed to be a metallic sulfide mineral inclusion, surrounded by a black, graphitized feather. Photomicrograph by Nathan Renfro; horizontal field of view is 1.08 mm.
Many yellow natural diamonds with isolated nitrogen occur as irregularly shaped rough crystals, often with inward faces in the form of re-entrant cubes. The rough diamonds from the Zimmi mine, however, showed smooth and rounded dodecahedral shapes. This rounded shape makes them much more suitable for cutting with minimal weight loss.

Type Ib diamonds are uncommon because with time and heat, isolated nitrogen impurities in the lattice tend to aggregate, forming more-complex defects that are characteristic of type IaA and IaB diamonds. The youngest dated diamonds are about a billion years old, and the youngest emplacement ages of diamondiferous kimberlites are less than 80 million years old. This suggests that nearly all diamonds spend most of their existence at great depths in the lower crust and upper mantle. It is unclear exactly how the isolated nitrogen impurities in type Ib diamonds avoided the aggregation process. This mystery makes the discovery of many “Canary yellow” diamonds from a single mine in Sierra Leone even more interesting, offering a potential tool for research into the formation and survival of type Ib diamonds in nature. Source: GIA @topic:7


Title: Black Diamond with Unusual Color Origin Abstract: Figure 1. A face-up view of the black diamond. Photo by Robison McMurtry.

              A 1.75 ct Fancy black round brilliant diamond (figure 1) was submitted to the Carlsbad laboratory for color origin determination. Natural black diamonds are usually colored by inclusions of sulfides, graphite or other mineral inclusions or, in rare cases, hydrogen-related clouds thatextend throughout the stone. Treated black diamonds are generally heavily fractured stones that are subjected to high-temperature, low-pressure treatment, which graphitizes the fractures, turning them black. Artificial irradiation can also produce a dark enough color so as to appear black, but this is less common (H. Kitawaki, “Gem diamonds: Causes and colors,” New Diamond and Frontier Carbon Technology, Vol. 17, No. 3, 2007, pp. 119–126).

Upon initial examination, the stone was noted to be covered in large, deeply penetrating fractures; therefore, high-pressure, low-temperature treatment was suspected. Yet closer examination revealed that the fractures were surrounded by dark brown radiation stains. Patches of non-fractured surface on the pavilion showed the normal transparency of diamond, causing the radiation staining to stand out in relief. Because radiation stains in diamond are inert to short-wave ultraviolet light, we placed the stone in a DTC DiamondView to confirm their identity. Figure 2 shows numerous fractures surrounded by dark bands, which are the radiation stains.

	Figure 2. A DiamondView image showing the pattern of inert radiation stains following the fractures in the stone. Image by Troy Ardon.

	Figure 3. This image of the pavilion shows the patchwork nature of the radiation staining. Photomicrograph by Troy Ardon; magnified 55×.
Natural radiation stains provide an important clue to the color origin of a diamond. Diamonds that have been naturally colored by radiation can have stains associated with that color, though this is not a definitive criterion. In this case, the stains are so numerous and thick that they cause the diamond color. A close-up view of the pavilion (figure 3) shows the relative transparency of the diamond contrasted with the highly saturated color of the radiation staining of the fractures. The coverage of the stains is so complete that only a few transparent areas canbe seen in the face-up view. Some of the color was due to the presence of small black inclusions, but most was due solely to the natural radiation stains, an unusual cause of color. Source: GIA @topic:4


Title: Diamond Market Sentiment Continues to Improve Abstract: Diamond manufacturers, with an eye toward the JCK Las Vegas Show in May, say market sentiment has strongly improved since January thanks in large part to better-than-expected orders from U.S. retailers.

The improvement in market sentiment has stabilized polished diamond prices, which had been weakening for months, and touched off a new wave of speculative buying of rough diamonds on the belief that supplies will be short after nearly a year of reduced sales into the market.

De Beers offered a relatively cautious sight – about $665 million, with some price increases averaging about 5% – to grab some of the rising premiums manufacturers are paying for sight goods.

While some dealers are predicting supply shortages in coming months, it has become extremely difficult to accurately predict the supply situation because of the large amounts of rough held for speculative buying and the very large polished inventories held in dealers’ safes around the world.

Inventories of polished goods have swelled in recent years because, after more than a decade of trying, the major diamond industry banks have succeeded in greatly limiting the use of memo to large U.S. retailers. Bankers are unwilling to offer an estimate on the percentage of current memo business, but say it is generally limited to its original purpose of supplying short-term seasonal needs.

The catalyst for ending the widespread use of memo was the spate of trade and retail bankruptcies in 2007-8 that resulted in hundreds of millions of dollars’ worth of disputed (or missing) diamond inventories and costly legal battles over ownership.

De Beers CEO Varda Shine offered her company’s outlook for the diamond market at a recent diamond conference in Dubai:

		Retail diamond demand will grow 5.5-6% on average by value each year, with most of that growth centered in India, China, Turkey and the Middle East. The U.S. will also grow, though more slowly.

		In 2016, the U.S. will represent 35% of world diamond sales; India 13%, China/Hong Kong 17% (Taiwan 2%); Japan 7%; the Gulf Region 9%; and Turkey 2%.

		Diamond production will begin to recede after 2017. Botswana (23%), Russia (22%) and Canada (12%) will be the world’s largest producers by value.

		Producing nations will continue to press for greater control over their resources: Botswana, Namibia and Canada are pressing for a minimum of 10% of their production to be processed locally. These nations are also developing branding efforts to aid this goal.

The conference, organized by the Dubai Multi Commodities Commission, focused on the changing distribution patterns of the diamond trade in light of emerging markets in China, India and the Middle East. Source: GIA @topic:8


Title: Adventures in Yakutia: On the Track of the Diamonds Abstract: This article starts with a brief history of Yakutian diamond production, from Mikhail V. Lomonosov’s theory of diamond deposits in 1761 to the discovery of the first kimberlites in 1954 to present-day operations. The bulk of the article then presents information the authors gathered during two visits to Yakutia, focusing on Mirny.

The report contains a map and a list of data on the most important mines. It is lavishly illustrated with images of Mirny—the mine, the town, the museum—and impressive diamond specimens.

Abstracted by Rolf Tatje Source: GIA @topic:7


Title: Very Large CVD Synthetic Diamond Abstract: Figure 1. This 2.16 ct marquise (13.42 × 6.73 × 3.94 mm) is the largest CVD synthetic diamond tested by GIA. It had J/K color, with a brownish tint. Photo by Jian Xin (Jae) Liao.

                      In the last decade, we have witnessed rapid improvement in the quality and size of lab-grown CVD synthetic diamonds. The GIA New York laboratory recently tested a 2.16 ct CVD synthetic from Scio Diamond Technology Corp. (figure 1), the largest specimen GIA has seen so far.

This marquise, which measured 13.42 x 6.73 x 3.94 mm, was more than twice the size of a 1.05 ct pear shape examined in 2010, previously the largest CVD synthetic tested by GIA (see Summer 2010 G&G Lab Notes, pp. 143–144). It had J/K color with a brownish tint, and microscopic observation revealed small fractures, pinpoints, and non-diamond-carbon black inclusions, resulting in an SI2 clarity grade.

The mid-infrared absorption spectrum showed the features of type IIa diamond. It was very pure in the infrared region, with no nitrogen- or hydrogen-related absorption features. Photoluminescence analysis at liquid-nitrogen temperature with varying laser excitations displayed typical CVD features: very strong emissions from N-V centers, moderate emission lines at 736.6/736.9 nm from the [Si-V]- center, and the CVD-specific 596/597 nm pair (figure 2). Also detected was weak emission from the H3 defect with a zero-phonon line at 503.1 nm, making for an interesting combination of optical centers. Under the short-wave UV radiation of the DiamondView, the table and crown facets showed pure blue fluorescence while the pavilion displayed banded orange fluorescence with irregular blue fluorescence regions. Very strong internal stress with irregular patterns was confirmed under the microscope using cross-polarized light.

	Figure 2. The 2.16 ct synthetic showed typical photoluminescence features of CVD growth, including strong emissions from N-V centers at 575 and 637 nm, moderate CVD-specific emissions at 596/597 nm, and 736.6 and 736.9 nm emissions from the [Si-V]– center.
Testing of this large, gem-quality CVD synthetic underscored the rapid improvement of lab-grown diamond technology. It is foreseeable that more of these products will continue to reach the jewelry industry.

Read More Lab Notes. Source: GIA @topic:4


Title: Fall 2007 G&G Book Reviews Abstract: “Adventures at the Bench: Tricks to Overcome a Jeweler’s Daily Challenges”
By Juergen Maerz, 110 pp., illus., publ. by MJSA Press [www.mjsa.org], Providence, RI, 2006. US$34.95

“Jeweled Garden: A Colorful History of Gems, Jewels, and Nature”
By Suzanne Tennenbaum and Janet Zapata, 216 pp., illus., publ. by The Vendome Press, New York, 2006. US$50.00

“Pedras Preciosas No Arte e Devoção: Tesouros Gemológicos na Arquidiocese de Évora [Precious Stones in Art and Devotion: Gemstone Treasures of the Archdiocese of Évora]”
By Rui Galopim de Carvalho, 154 pp., illus., publ. by Fundação Eugênio de Almeida, Évora, Portugal, 2006 [in Portuguese and English, no price information available]

“Shamelessly: Jewelry from Kenneth Jay Lane”
By Nancy N. Schiffer, 240 pp., illus., publ. by Schiffer Publishing Ltd. [http://www.schifferbooks.com], Atglen, PA, 2007. US$59.95

“Costume Jewelry for Haute Couture”
By Florence Muller, 271 pp., illus., publ. by The Vendome Press, New York, 2007. US$75.00

“Pearl Oyster Information Bulletin, No. 17”
By various authors, 48 pp., illus., publ. by the Secretariat of the Pacific Community, www.spc.int/Coastfish/ News/POIB/17/POIB17.pdf, December 2006, free

“The Jeweled Menagerie: The World of Animals in Gems”
By Suzanne Tennenbaum and Janet Zapata, 216 pp., illus., publ. by Thames & Hudson, New York, 2007, US$34.95

“Kimberlite and Related Rocks of India”
By Fareeduddin and M. S. Rao, Eds., 271 pp., illus., publ. by the Geological Society of India [www.gsi.gov.in], Bangalore, 2007, Rs20

“Paraíba Tourmaline “Electric Blue Brilliance Burnt into Our Minds”
By Masashi Furuya, 23 pp., illus., publ. by the Japan Germany Gemmological Laboratory [jggl@sapphire.co.jp], Kofu, Japan, 2007, ¥1,500

“The Geology of Gem Deposits”
by Lee A. Groat, 276 pp., illus., publ. by the Mineralogical Association of Canada [www.mineralogicalassociation.ca], Quebec, 2007, US$50.00

To view the full section, download the PDF above. Source: GIA @topic:6


Title: Winter 2016 G&G: Exploring Jaipur’s Gem Industry, New Gem Sources, and Inclusions in Emerald Abstract: In recent years, the Indian city of Jaipur has emerged as a cutting, manufacturing, and retail powerhouse. The lead
article in this issue looks at the city’s history and profiles some of its more prominent jewelers. The cover shows a
bracelet created by Jaipur’s Birdhichand Ghanshyamdas Jewellers. Inspired by the Amer Fort, a UNESCO World
Heritage Site, the bracelet is comprised of canary diamonds, polki diamonds, and a stunning emerald at its center.
Photo by Robert Weldon/GIA, courtesy of Birdhichand Ghanshyamdas Jewellers.

	The Winter 2016 issue of Gems & Gemology boasts a wealth of information blending the old and the new. The lead article profiles the emerging powerhouse of Jaipur, India. The legendary colored gemstone cutting center has become a jewelry manufacturing and retail giant to rival other major players in the industry. Other features include the early synthetic emeralds of Richard Nacken, Vietnamese danburite, and field report from Mozambique, and a wall chart of emerald inclusions.

	JAIPUR, INDIA: THE GLOBAL GEM AND JEWELRY POWER OF THE PINK CITY

	Rubies in a modern invisible setting are combined with polki diamonds in this fusion-style ring. Photo courtesy of Birdhichand Ghanshyamdas Jewellers.

The northern Indian city of Jaipur, long a center for colored gemstone cutting, has expanded to include jewelry design, manufacture, and retail. A team led by Andrew Lucas and Nirupa Bhatt explores the city’s historical relevance to the gem trade and visits several local manufacturers and retailers to examine the scope and impact of their operations.

	SYNTHETIC EMERALDS GROWN BY RICHARD NACKEN

	Synthetic emeralds produced by Richard Nacken in the mid-1920s. Nacken left these and other samples to his family, and they are now in the possession of his grandsons. Photo courtesy of E. Schlatter.

	Dr. Karl Schmetzer and his coauthors recount an important milestone in gemology: the first gem-quality synthetic emeralds of facetable size. The article reviews the events that led to Nacken’s successful emerald growth, along with the chemical, morphological, and microscopic properties of his production. They also address longstanding speculation that Nacken collaborated with IG Farben on synthetic emerald growth.

	A NEW FIND OF DANBURITE IN THE LUC YEN MINING AREA, VIETNAM

	Five rough danburite crystals, in sizes up to 2.5 cm, were found at the Bai Cat deposit in Luc Yen, Vietnam. One, weighing 26.3 ct in rough form, was cut into the 4.6 ct faceted oval. Photos by Le Thi-Thu Huong.

Danburite has been discovered in the gem-rich region of Luc Yen, Vietnam. The rare material, found in 2015, is honey yellow in color and shows excellent transparency. A team led by Le Thi-Thu Huong investigates the properties of this new find.

	INCLUSIONS IN NATURAL, SYNTHETIC, AND TREATED EMERALD

	This emerald contains a brown crystal of the rare mineral parisite. There is also an oil-filled cavity showing a blue and orange flash effect, along with two large trapped gas bubbles. This inclusion suite verifies the natural origin of this emerald; it also confirms that the stone, which shows signs of clarity enhancement, is from Colombia. Photomicrograph by John I. Koivula; field of view 3 mm.

	The Winter issue boasts a new wall chart displaying common inclusions found in natural, synthetic, and treated emerald. Among the contributors to the chart are inclusion specialists John Koivula, Nathan Renfro, Jonathan Muyal, and Shane McClure. The accompanying article provides a brief overview of inclusion studies.

	UPDATE ON GEMSTONE MINING IN NORTHERN MOZAMBIQUE

	A parcel of mainly green and yellow tourmaline from Ocua, Mozambique. Photo by Vincent Pardieu/GIA.

	In 2016, a field gemology team from GIA Bangkok traveled to northern Mozambique to visit the world’s largest ruby source and to observe developments at various new deposits. The resulting field report by Wim Vertriest and Vincent Pardieu documents production of ruby, spinel, and tourmaline in the region, as well as plans for future operations.

	LAB NOTES

	Updates from GIA’s labs around the world include reports on a CVD synthetic diamond weighing over 5 ct, the largest HPHT synthetic diamond to date, and synthetic sapphire and synthetic spinel doublets.

	MICRO-WORLD

G&G’s photomicrography section features entries on chalcedony with quartz windows showing Brazil-law twinning, a demantoid from Namibia with sphalerite inclusions, and a feldspar with an apatite cluster just below the surface.

	GEM NEWS INTERNATIONAL

	Sapphire production from one day of mining in Tasmania. The trapiche-type sapphire in the center weighs 2.73 ct. Photo by Vincent Pardieu/GIA.

	The Winter GNI section includes a crystal of blue dravite-uvite tourmaline from Afghanistan’s Koksha Valley, a look at “trapiche-type” sapphire from Tasmania, and an investigation of “decorated” jadeite jade.

	2016 DR. EDWARD J. GÜBELIN MOST VALUABLE ARTICLE AWARD

	Readers are invited to vote for the Most Valuable Article from 2016. Click here to vote for the top three articles from our contributors; voting will remain open until Monday, March 7, 2017. All ballots will be entered into a drawing to win a one-year subscription to G&G. Source: GIA @topic:7


Title: Lapis-Lazuli from Sar-E-Sang, Badakhshan, Afghanistan Abstract: The lapis-lazuli deposits at Sar-e-Sang in Badakhshan, Afghanistan, have provided the raw material for objects fashioned of this stone since the earliest civilizations. The mine, which lies in the Hindu-Kush Mountains, is difficult to reach and, because of climatic conditions, is opened only a few months during the summer. The lapis is found in veins in which calcite and dolomite are intimately associated with silicates such as diopside, scapolite, and forsterite. Pyrite is always present; the pure blue mineral is lazurite. The color of the lapis-lazuli varies according to the amount of the various impurities contained therein. Well-formed crystals of lazurite with the dominant {110] shape are rarely found. This article examines the crystallographic properties of lapis-lazuli, the site of Sar-e-Sang and the lapis-lazuli deposits there, and offers an explanation for the genesis of the material. Source: GIA @topic:2


Title: Summer 2004 G&G Book Reviews Abstract: “Secrets of the Gem Trade: The Connoisseur’s Guide to Precious Gemstones”
By Richard W. Wise, 274 pp., illus., publ. by Brunswick House Press, Lenox, MA, 2003. US$79.95

“The Gem Hunter: True Adventures of an American in Afghanistan”
By Gary W. Bowersox, 505 pp., illus., publ. by Geovision, Inc., Honolulu, HI, 2004. US$29.95

“Gem and Ornamental Materials of Organic Origin”
By Maggie Campbell Pedersen, 268 pp., illus., publ. by Elsevier Butterworth-Heinemann, 2004. US$54.95

To view the full section, download the PDF above. Source: GIA @topic:9


Title: An Unusual Partially Non-Nacreous Pinctada radiata Natural Blister Pearl Abstract: Figure 1. Pinctada radiata shell with a natural blister pearl measuring approximately 11.39 × 9.31 × 8.69 mm. Photo by Gaurav Bera.
The vast majority of pearls produced by the different Pinctada species display a lustrous nacreous surface structure. However, a small percentage of these pearls exhibit non-nacreous surfaces. GIA’s Mumbai laboratory received one very interesting example for scientific examination: a partially non-nacreous natural blister pearl, obtained from the waters of Bahrain by a noted pearl diver in March 2023.
The shell weighed 21 g and measured approximately 64.55 × 63.90 × 7.72 mm. The back of the shell showed fine layered striations toward one end and areas of massive parasite holes toward the center and hinge area. The inner surface was silvery cream in color with strong orient and held a large light cream and brownish black baroque pearl, measuring approximately 11.39 × 9.31 × 8.69 mm, attached close to the upper mantle-lip area (figure 1). This blister pearl was very unusual compared to those typically found in the Pinctada radiata mollusk. Viewed under 40× magnification, the inner shell’s brown edges exhibited columnar calcite honeycomb-like structures, while the white portion displayed the typical platy structure of fine nacreous overlapping aragonite platelets, presenting a chalky appearance near the hinge. Surrounding the central blister pearl was a yellowish brown region consisting of desiccated organic matter.

Figure 2. Left: Partially non-nacreous blister pearl showing significant surface-reaching cracks (blue arrow) and a distinct delineated step feature separating the light cream area from the adjacent black area (red arrow). Right: A columnar honeycomb-like calcite structure was observed at the edge of the step feature; field of view 14.40 mm. Photos by Karan Rajguru.
A closer look at the light cream, strongly iridescent section of the blister pearl with the distinctive platy structure looked more like “fingerprints,” distinctly separated by a delineated step feature from the adjacent black area. The black region was noticeably dull and matte and covered by a translucent layer revealing circular botryoidal surface spirals with a calcitic columnar pattern. Additionally, significant surface-reaching cracks were present in the translucent black area along the columnar structures (figure 2, left). Within the non-nacreous “cellular” structure, a layer had peeled off, accentuating the light cream calcitic step feature (figure 2, right).

Figure 3. Left: A real-time microradiograph image showing the internal structure of the blister pearl consisting of an organic-rich core surrounded by concentric growth arcs (red arrow) with parasite holes in the host shell (blue arrow). Right: Strong orangy red reaction under long-wave UV light, observed on the edge of the shell and part of the black area on the blister pearl. Photos by Lubna Sahani (left) and Gaurav Bera (right).
Real-time microradiography imaging of the blister pearl and its host shell revealed a distinct outline showing the point of attachment of the pearl to the shell. An organic-rich core with contrasting patchy light and dark gray areas occupied almost half of the pearl’s internal structure (figure 3, left). This was surrounded by concentric growth arcs, which are classic features of natural pearl structures, similar to those observed in known Pinctada radiata pearls from GIA’s research database. In addition, significant cracks extending from the pearl to the shell and parasite tubes forming a dendritic pattern in the host shell were seen when the pearl was X-rayed in other directions. The structure indicated a natural whole pearl that had attached itself to the host shell (“Natural shell blisters and blister pearls: What’s the difference?” GIA Research News, August 26, 2019).
Due to the limitations imposed by the size of the shell, it was not possible to collect chemical data on the pearl using energy-dispersive X-ray fluorescence spectrometry. However, both shell and pearl showed an inert reaction when exposed to X-ray fluorescence, indicative of its saltwater origin. An interesting reaction was observed under long-wave ultraviolet light. The edge of the shell and part of the black area on the pearl showed a strong orangy red fluorescence, while the inner part of the shell displayed a weak blue reaction (figure 3, right). The shell was inert under short-wave UV. Similar reactions linked to a type of porphyrin pigment have been observed in partially non-nacreous and nacreous pearls from the Pteria species (S. Karampelas, “Black non-nacreous natural pearls from Pteria species,” Journal of Gemmology, Vol. 35, No. 7, 2017, pp. 590–592). Raman spectroscopy using 514 nm and 814 nm laser excitation revealed peaks at 701/704 cm–1 and 1086 cm–1, indicative of aragonite. Due to high fluorescence, no calcitic peaks were observed in the non-nacreous area. Photoluminescence spectra collected from both the shell and the blister pearl revealed three broad peaks centered at 620, 650, and 680 nm, which are characteristic of some naturally colored pearls.
Formation of natural blister pearls in the wild has always been an interesting topic of research for gemological laboratories. The studied sample is certainly noteworthy due to its size, partially non-nacreous structure, and unique reaction under long-wave ultraviolet light. Source: GIA @topic:5


Title: Saltwater Clamshell Beads (Tridacna Species) Used in Freshwater Cultured Pearls Abstract: Figure 1. A strand of baroque-shaped freshwater bead cultured pearls shown with two Tridacna-species mollusk shells from GIA’s shell reference collection. Each sample weighs approximately 20 ct, ranging from 16.73 × 12.58 × 12.49 mm to 18.98 × 13.53 × 13.43 mm. Photo by Nuttapol Kitdee.
GIA’s Bangkok laboratory recently studied 23 intriguing freshwater bead cultured pearls purchased from a vendor in Hong Kong. They displayed an elongated baroque shape with a surface protuberance at one end, and they weighed approximately 20 ct apiece and ranged from 16.73 × 12.58 × 12.49 mm to 18.98 × 13.53 × 13.43 mm (figure 1). Their shape and appearance are similar to saltwater bead cultured pearls known in the market as “Tokki pearls” (A. Homkrajae et al., “Internal structures of known Pinctada maxima pearls: Cultured pearls from operated marine mollusks,” Fall 2021 G&G, pp. 186–205).

Figure 2. RTX imaging revealed shell bead nuclei approximately 12 mm in diameter entirely covered by the pearl’s approximately 1 mm thick nacre (left), with numerous parasite channels in the beads (right).
Real-time microradiography (RTX) revealed the distinct round demarcation of a bead nucleus with additional void and/or linear features in all the samples, as expected from their external appearance (figure 2, left). However, the beads were more radiopaque and appeared lighter gray in RTX imaging than the traditional freshwater shell bead nuclei widely used in both saltwater and freshwater bead cultured pearl production (P. Southgate and J. Lucas, The Pearl Oyster, 2008, p. 286; “Freshwater pearling in Tennessee,” GIA Research News, October 7, 2016; N. Sturman et al., “Vietnam: Shell nuclei, pearl hatcheries, and pearl farming,” Fall 2020 G&G, pp. 402–415). Numerous long, thick parasite tubes were visible within the beads, something not often seen in traditional beads (figure 2, right). Optical X-ray fluorescence imaging was used to verify the pearls’ freshwater origin. They exhibited weak to moderate yellowish green fluorescence, confirming a freshwater origin. However, the reaction was much weaker than many freshwater bead cultured pearls of the same size and nacre thickness previously examined. These unusual characteristics observed in RTX and X-ray fluorescence imaging led us to cut two pearls in half to investigate the bead nuclei.

Figure 3. Left: A cross section with the Tridacna fashioned shell bead nucleus inside showing fine subtle flames in between banded structures. Right: Magnified view of the clamshell bead’s flame structure. Photomicrographs by Kwanreun Lawanwong; fields of view 19.20 mm (left) and 7.20 mm (right).
The cross sections revealed bead nuclei approximately 12 mm in diameter. The beads appeared chalky white and opaque, unlike traditional beads that are commonly white to cream-colored and semitranslucent. Moreover, the beads exhibited a porcelain-like texture and a subtle flame pattern. We ground the surface of two additional samples to better understand the material. Banded structures of shell formation with subtle flame structures in between were present (figure 3).

Figure 4. An X-ray illuminated cross section produced a strong yellowish green fluorescence reaction on the freshwater pearl’s outermost surface nacre layer, while the inner rounded saltwater clamshell beads showed an inert reaction.
Energy-dispersive X-ray fluorescence was used to analyze the elemental concentration of the outer nacre layer and the bead nuclei. The nacre layer showed a high level of manganese and low strontium content, confirming the pearls formed in a freshwater environment. Conversely, the bead nuclei showed high strontium (around 1000 ppm) and no manganese was detected, which are typical results for pearls from a saltwater environment. X-ray fluorescence imaging of the cross section displayed a strong yellowish green reaction on the freshwater nacre due to high manganese content, while the saltwater bead nuclei were inert (figure 4). A Raman spectrometer with 514 nm argon-ion laser excitation was employed to analyze the bead nuclei composition, and double peaks at 701 and 705 cm–1 and a single peak at 1085 cm–1 of aragonite were recorded. Aragonite is a common component of shell and pearl.
The large size, white color, porcelain surface appearance, banded structure with flames, saltwater formation environment, and aragonite composition of the bead nuclei suggested they were created from the clamshell of Tridacna-species mollusks. Fashioned shells from Tridacna species have been applied particularly in pearl imitations (see Summer 2014 Lab Notes, pp. 153–154; Spring 2015 Lab Notes, pp. 62–63) but are not commonly used in culturing because they are easily broken during the drilling process. More importantly, shells from Tridacna species should be avoided for jewelry items or decoration since they are protected by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the international agreement that protects endangered species. Source: GIA @topic:5