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

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

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

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

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

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

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

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

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

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

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

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

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

	Dating Diamonds

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

View Gallery

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

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

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

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

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

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

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

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

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

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

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

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

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

	Preparing Diamonds for Study

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	Separating Rhenium and Osmium

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

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

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

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

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

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

	Using Mass Spectroscopy

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

“That’s actually a fun part about my job,” he continues, “I get to be a teacher and a mentor, and that turns out to be a lot of fun.” Source: GIA @topic:4


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

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

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

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

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

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

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

Through a unique combination of hands-on training, one-on-one coaching and multimedia, students of GIA’s Diamond Grading Lab class learn techniques for grading diamonds consistently and accurately using a modern gem microscope and a jeweler’s loupe. By the end of the five-day program, participants are versed on GIA’s International Diamond Grading System™ and how it determines diamond value, the components of a GIA Diamond Grading Report, the most common diamond features, and how to operate gemological equipment. For more details about GIA education programs, contact us or call +1 760-603-4001. Source: GIA @topic:8


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

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

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

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

	The volume, while certainly not exhaustive on any of the topics it addresses, offers a balanced cross-section of the development issues facing the diamond industry today. However, there is very little about the changing economics of the diamond industry—the multichannel rough market, competitive auctions, and the changing role of banks, to name a few—that ultimately have the greatest effect on its development. Source: GIA @topic:8


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

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

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

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

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

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

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

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

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

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

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

	ROUGH DIAMONDS

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

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

	Alrosa, the world’s largest producer by volume, estimated its yearly production will be 37 to 39 million carats, equal, to or slightly lower than 2015 levels. The company withheld 22 millions carats from the market last year as demand collapsed in the second half. The company stated that it wants to sell down the stocks it accumulated last year, while also selling new production, but keeping prices stable. Source: GIA @topic:8


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

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

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

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

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

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


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

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

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

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

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

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

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

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

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

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

Polnauer graduated from GIA with his GG diploma in 2004.

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

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

He advises incoming GIA students to follow a similar course.

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

	Shmulik Polnauer won the Prosperity Pink Diamond (left) at the 2011 Argyle Pink Diamond Tender as a 1.71 ct, Fancy Intense Purplish Pink, radiant-cut diamond. After deciding to repolish the stone to improve its color intensity, Polnauer brought the Prosperity Pink to a 1.68 ct, Fancy Vivid Purplish Pink. It was offered for $1 million. The Purple Orchid (right), offered for $4 million at the 2014 Hong Kong Jewellery & Gem Fair, came from a South African mine and weighed 4-plus carats. Polnauer bought the rough stone in India and transformed it to a 3.37 ct, Fancy Intense Pinkish Purple VS2 diamond. Photo courtesy Leibish & Co. Source: GIA @topic:8


Title: January Outlook: Rough Diamond Supplies Up, Prices Down Abstract: Holiday retail diamond jewelry sales in the U.S. were spotty, but in positive territory overall, according to preliminary reports. Demand appeared to be sufficient to clear some of the inventory backlog that plagued the diamond trading centers the previous year. Photo by Eric Welch/GIA, courtesy Finell’s Jewelers

	De Beers ramped up its sales of rough diamonds to $540 million at its Jan. 18-22 sight and reportedly cut prices an average of 7%. The company cut sales to the lowest level in decades during the final quarter of 2015, while the trade grappled with softening prices and excess inventories.

	Fortunately, a respectable, if not exciting, holiday season helped reduce excess diamond inventories sitting in world diamond manufacturing centers. As the holidays drew near, dealers in the U.S. began to cite shortages of some goods – specifically light sizes (a few points under landmark carat weight i.e., 0.45-0.49 carats) and medium colors and clarities.

	Preliminary reports indicate that U.S. retail jewelry sales will be slightly up for the year by dollar volume. Sales volume will likely be 4% to 5% higher than the dollar figure compared to 2014, because prices for gold and diamonds declined 10% to15% during the year. These price declines enabled the major chains to engage in aggressive discounting during the season, without seriously compromising their bottom line.

	Signet Group reported its same store sale rose a strong 4.9%, for the eight-week season, with its Kay Jewelers division showing a 7% increase and its Jared stores up 9%. The company’s Zale division rose 2.3%.

	Aggressive discounting by its competition in a restrained consumer market caused Tiffany & Co.’s, same-store holiday sales to fall by 8% in North America. (Tiffany rarely runs discount promotions.) A strong U.S. dollar also contributed to the decline as tourist traffic, which accounts for a substantial percentage of the company’s New York sales, was down.

	Overall, Tiffany’s same-store sales were down 5%, though it maintained strong profit margins. A company statement said it expected no significant improvement this year.

	Centurion’s 2015 holiday season survey of luxury independents around the U.S. found generally positive, but mixed, results: 19.6% of respondents said their holiday sales grew significantly − more than 10% − over last year’s holiday. But an equal number saw declines of more than 10% over last year. In total, 58% of respondents were at least even or somewhat ahead of last year’s holiday sales figures, while 42% experienced a drop in holiday sales.

	Most of those who reported declines, however, blamed the absence of a few key sales in 2015, which spiked their numbers in 2014. The trend was toward larger numbers of lower ticket sales. Additionally, many do business in areas where oil and gas industries dominate their economies.

	CHINA’S RETAIL OUTLOOK

	The outlook for retail sales for Chinese New Year (Feb. 8) is looking gloomy as the country’s stock market appears to be headed for a severe slump.

	The region’s largest jewelry retailer, Chow Tai Fook, based in Hong Kong, reported that same-store-sales dropped 11% year-on-year in the third fiscal quarter that ended Dec. 31. Sales in Hong Kong and Macau dropped 20%, while income from the mainland was off 6%. Another Hong Kong-based jewelry chain, Luk Fook, reported that same-store-earnings plunged 26% in Hong Kong during the third quarter of 2015, compared to the previous year, with its mainland stores showing a decline of 10%. The company said sales of gem-set jewelry declined 27% in Hong Kong, but rose 2% in the mainland.

	Some analysts have suspected for a year or more that the government may have been trying to hide the fact that the country is in recession, not just experiencing slower growth. One indicator is that Chinese retail sales, including jewelry, have been in negative territory for some time. This is unlikely to improve because the Renminbi Yuan has resumed its decline against the U.S. dollar, making diamonds and gold more costly in local currency.

	While China’s slumping stock market has caused markets in the U.S. and Europe to decline in its wake, economists believe it is a short term reaction to the situation and not a reflection of economic conditions outside of the country.

	Diamond Rough

	On the diamond supply side, all eyes are focused on De Beers’ January sight. Its parent company, Anglo American, has taken a huge financial hit and as its biggest earner, De Beers is under heavy pressure to bring in revenue. The recovery of the diamond market, however, while real, remains very fragile. A large sight (if clients do not refuse the goods) or token price reductions that do not allow manufacturers to make a profit, could compromise the upturn or start a price/supply conflict with Alrosa and Rio Tinto, both of which have pressures of their own.

	De Beers did announce it would close its Snap Lake mine in northern Canada, which produced about 1.2 million carats last year. The mine ran into major cost overruns and has been unprofitable from the outset.

	At the same time, dissident shareholders of Dominion Diamond Company (owner of Ekati and partner in Diavik) have called on management to resign for failing to plot a growth strategy beyond its existing mines. The dissident group, which holds a 5% stake in the company, is also demanding representation on the board of directors. Two board members resigned from the company on Jan 5. It is unclear whether or not they were related to the shareholder action.

	Colored stone demand has been improving, but many primary dealers continue to hold out for prices that the trade deems unrealistically high. This dampened sales at the fall Hong Kong show, where it was obvious that Chinese buyers were no longer in the market in a big way. Many dealers have not yet absorbed that message. Source: GIA @topic:8


Title: Begin with the End in Mind: Tips, Tools to Evaluate Diamond Rough Abstract: Chandra Horn, academic director for Canada’s Montreal School of Gemmology, said that when evaluating diamond rough, “You’re always imagining, ‘What’s going to come out of this? What’s in there?’” Photo by Kevin Schumacher/GIA

                      Equipped with a 10× jeweler’s loupe, a millimeter measuring gauge and a standard calculator, artisanal miners around the world have everything they need to determine realistic – and profitable – values of the diamond rough they mine by hand. A copy of the Rapaport Diamond Report wouldn’t hurt, either, said Chandra Horn, associate director of the Ecole de Gemmologie de Montreal, in an October 2015 lecture to students at GIA’s Carlsbad campus.

Horn said the challenge for artisanal miners – who make up a significant percentage of her school’s student population – is a lack of access to evaluation software used by large-scale manufacturing facilities or organizations, such as DTC/De Beers. They also have fewer samples of rough to compare their finds with to help them determine what manufacturing and other costs will be.

The key, Horn said, is to begin with the end in mind – considering the final product through each step of the evaluation.

“The whole goal of these gems is to end up as a finished product,” said Horn, who also teaches rough diamond evaluation. “When we start looking at how to value and grade these diamonds, it’s almost as if we have to pull out a crystal ball and look into their future and try and predict what they will become, in order for us to work backwards to see what value they have in their current state.”

Horn presented the “rough C’s,” or evaluation criteria, which she described as comparable to GIA’s 4Cs of diamond quality for polished stones:

4Cs for Polished Diamonds vs. Evaluation Factors for Rough Diamonds

				Polished

				Rough

				Carat Weight

				Carat Weight

				Cut

				Shape/Make (sometimes Model)

				Clarity

				Quality

				Color

				Color

With knowledge of those criteria, as well as the calculator, loupe and gauge, Horn said her students – and others without access to large-scale manufacturing operations – can effectively evaluate rough.

	Horn said DTC/DeBeers sorts diamond rough into 11,344 categories. While artisanal miners don’t use that many, a few simple tools give them everything they need to determine realistic, profitable values for the diamond rough they mine by hand. Photo by Kevin Schumacher/GIA

	First Steps: Size and Shape
The ideal first step, she said, is to sort a parcel of rough by size or carat weight. Miners and manufacturers must consider both how the rough (most frequently shaped as cubes, octahedrons or dodecahedrons) can be cut – considering the external and internal − and which polished shapes have the highest market values.

 “We are always looking to identify the shape so we know the orientation inside,” she said.

“Cutters have to pay attention to and respect the internal grain, whether that is the cleavage direction or differential hardness we see in diamonds. These are going to dictate what it is we can do with these stones.”

When a stone’s internal directions aren’t obvious, Horn said that unique surface features can provide clues. “The tiniest little octahedron is going to tell the cutter where they are and what direction they’re looking at.”

Horn reiterated that the rough’s final shape plays a huge role in the process, too. Most of the time, particularly when people are not evaluating for a large manufacturing facility, round brilliants will be the most desirable final shape.

“Why? Because rounds are what sell,” Horn said. “Rounds are what we see in the marketplace, and rounds are not going to sit in your safe.”

She acknowledged, though, that there was a great opportunity for profit if the next up-and-coming jewelry designer in the student lecture hall could figure out how to promote triangle-shaped diamond engagement rings.

“A triangle-shaped engagement ring trend could change the value of the macle (triangular-shaped rough),” she said. “If you can create a market for them, there are lots of these stones out there. A lot of rough dealers have these stones and it’s not worth it to them to cut them as triangles.”

	“When you work with rough, you’re always looking for the outline of your stone,” Horn said. Photo by Kevin Schumacher/GIA

	Rough Quality: Inclusions
Diamond rough’s quality – the equivalent to polished goods’ clarity – is the next aspect for evaluation. Inclusions and their reflections, as well as areas of stress and strain, must be considered.

“Inclusions can change what you can do with a stone,” Horn said. “Not only do you have to have an understanding of a little bit of crystallography and a little bit of what the cutter or manufacturer is going to do, but you definitely have to understand how the diamond grader is going to look at this finished product. What effect is that going to have on how this is graded as a polished stone?”

Showing the audience examples on the screen, Horn demonstrated how inclusions can be surrounded by areas of stress or strain.

“Pockets of stress areas and strain can lead to the stone literally exploding and/or shattering while we are trying to saw it, polish it or place a facet on it,” Horn said. “Usually, (it’s the cutter’s job) to avoid this, but if you’re buying or valuing or grading rough diamonds, you have to be conscious of it, too. Because it just changed what we can do with this stone … it is no longer simple. We have to factor this in as a danger zone.”

The sawing process itself can present risks to an otherwise “clean” stone: Horn displayed a close-up image of a piece of rough from her own collection, with a feather that hadn’t existed prior to sawing.

“They were going to cut it, do an uneven split, and get a nice, round, large stone out of this,” she said. “And then boom!” The sawer was working along the correct saw plane, but “sped it up too much – was in a bit of a rush – and provoked this feather.”

	“Meticulous measuring and math – they’re not what I signed up for, but what I have fallen in love with,” said Horn. Photo by Kevin Schumacher/GIA

	Rough Color: Strike a Balance
Horn explained that when it comes to color, rough evaluation doesn’t utilize the whole alphabet. “There is no D or E,” she said. “It’s light, medium and color.”

In general, the “less is more” rule applies – except in the case of fancy colors, which are an entirely different proposition.

“The color’s not going to look the same once we get it cut,” she said, noting that people have to consider where the color concentration is and what balance it will strike in the polished stone. “With fancy-colored stones, you definitely want to be sure they are saturated colors.”

Horn said that in green diamonds, for example, which often have very thin stains that only penetrate the stone shallowly, the wrong cutter can take off too much “rough skin” and end up with a colorless diamond.

Pinks and browns, which are often seen in color zones, are also at risk in the hands of a cutter unskilled with colored diamonds.

“That zone – that little area that held that pink color – which, as you probably know, with some of the auction results in the last few years, adds a lot of zeroes to your value – you don’t want him to polish that off,” she said. “That would be a big mistake even if it came out as a D-color (polished stone).”

Horn said that overall, “a lot of factors” must be considered when evaluating rough, and “it’s all based on the prices for polished goods.”

“At the end of the day, it’s always going to come down to what kind of value will I get? What’s my yield going to be? What percentage of this rough am I going to be retaining in the cut product?” Horn said. “It’s always going to come back to math and finance.” Source: GIA @topic:7


Title: Bright Light at Midnight: Canada’s Far North Land of Diamonds Abstract: Immense glaciers leveled hills and carved thousands of lakes in Canada’s far north. They are pure as distilled water and remain partially frozen most of the year. Even in late June, the ice remained five feet thick in some spots. Photo courtesy Rio Tinto

                      Canada’s far north is a vast silent land of stark beauty, molded by mile-high glaciers that carved many thousands of deep ruts and pits, then, as they melted, filled them to create one of the world’s largest networks of lakes. Four of the world’s largest diamond mines are clustered around one these lakes, Lac de Gras.

The diamonds remained hidden until 20 years ago because the unforgiving climate deterred all but the hardiest of human beings – the northern First Nations tribes who have lived there for thousands of years, fishing and trapping for sustenance – from exploring the area.

	Arriving at Yellowknife, 62.4 degrees latitude, just before midnight in the June solstice, the sun is still well above the horizon. Photo by Russell Shor/GIA.
In the 10 weeks of summer at the 64th parallel there are literally endless days, with several weeks of 24-hour light. There is just enough time for the vegetation − dwarf birch, northern Labrador tea, blueberry, mountain cranberry and sphagnum moss − to survive as feed for the herds of caribou that migrate over the rocky terrain in the fall and spring.

The first freeze returns with a vengeance in late September and brings with it the spectacular lights of the Aurora Borealis. The guidebooks say this part of the world is the best place to see nature’s show, and 50,000 tourists journey to the northernmost cities, Whitehorse and Yellowknife, each fall for a view. By December, the temperatures are down to -40°C (-40°F) and there’s but a glimmer of twilight at noontime.

	Caribou are essential to the ecology of Canada’s northland. Photo courtesy of Rio Tinto
The few outsiders who ventured up to the area in the last century and a half were looking for treasure – gold at first, as with the Klondike gold rush of 1897–99. By the 1930s, gold prospectors moved farther east to the Northwest Territories and developed the provincial capital of Yellowknife. At 100 miles south of the tree line, the town sits on the north bank of the Great Slave Lake, near two gold mines. The Great Slave (named after the Slavey tribe that inhabits the area) is the world’s 10th largest lake, covering well over 10,000 square miles, and the deepest in North America, plunging more than 2,000 feet in some spots.

The tree groves that surrounded Yellowknife provided a nearly unlimited source of building materials, first for log cabins, then for processed wood beams and siding. As Yellowknife grew into the provincial capital, prospectors rarely ventured much farther north beyond the tree line, the gold mines wound down, and money stopped pouring into the town.

	Dr. James Shigley, GIA Distinguished Research Fellow, and Pedro Padua, a videographer for GIA, stand in front of one of Yellowknife’s first structures dating from 1935 when most of the settlement was built from logs. Photo by Russell Shor/GIA
A half-century later, another type of prospector came to the region – geologists searching for diamonds.

They were there for sure. People had been finding diamonds in rivers and creeks as far south as Montana in the U.S. for decades. De Beers wanted to find them first, dispatching exploration teams north in the 1980s toward the Mackenzie Mountains near the Yukon border. The team did discover garnets, chromites and ilmenites, minerals that told them diamonds could be nearby, but no diamond sources.

Yellowknife, the closest city at that time, was facing an economic decline, so when De Beers chose it as the staging area for exploration, the locals welcomed it. When the word went round that the De Beers was on the scene, others paid attention, including Superior Oil, a California-based company exploring the area for other minerals.

	Charles Fipke, left, and Stewart Blusson traversed the rugged and remote terrain of Canada’s Northwest Territories for years in their quest to find diamonds. Left photo by GIA; right photo courtesy of Stewart Blusson.
Superior Oil dispatched geologist Charles Fipke in the early 1980s and a team that included another geologist, Stewart Blusson, to the Mackenzies to explore for diamonds. They found the same indicator minerals as De Beers, but Standard Oil quickly lost interest in the project.

The two geologists knew they were on the trail, but it was Blusson, with his strong knowledge of the region’s glacial history, who understood that the glaciers were the key. They carried the indicator minerals across the expanse of barren land that also happened to host the oldest known rocks on Earth (more than 3.9 billion years), making this prime diamond country. The geologists kept up the search, using their own funds to follow the pyrope garnet trail eastward.

Blusson rented and piloted a helicopter to plot a course, setting Fipke on the ground to collect samples until the fall temperatures fell well into the minus range and daylight nearly disappeared. After three years, the composition of samples strongly suggested diamonds, but the money was running out, so Fipke embarked on a fundraising plan to sell shares in an exploration company he founded, DiaMet Minerals.

	Lichen covered rocks and sparse vegetation cover most of Canada’s far north where the growing season is only a few weeks. This is the type of terrain Fipke and Blusson traversed for years as they followed the trail of pyrope garnet. Photo by Russell Shor/GIA
Eight years into the search, the indicator minerals around one large lake were off the charts, but the money was again running out and the encroaching winter had made it impossible to continue. Fipke returned in April 1990, with the ground still frozen solid and enough money for one more day of digging. On that day, after hard digging, he and his team found more indicators, including a large chrome diopside, which told them they were practically standing on a kimberlite pipe.

With these samples, Fipke was able to convince the mining giant BHP to front the funds to finish the job in exchange for a 51% share. Eighteen months later, while war raged in Kuwait, the company announced it had found a world-class diamond deposit at the bottom of Lac de Gras.

	Diavik Mine

	Discover the expansive, beautiful and harsh environment of Canada’s Northwest Territories and go behind-the-scenes of a Canadian diamond mine.
Developing the deposit, which became the Ekati Mine, tested the ability of BHP to develop a large mine without compromising one of the world’s last pristine wildernesses. The lakes are as pure as when they were formed. Despite its barrenness, the area is home to five First Nation tribes (two branches of the Dene First Nation, the Tlicho peoples, the Kitikmewot Inuit and the North Slave Metis), all of whom follow the caribou herds for sustenance, maintaining an ecological balance that has endured for millennia. Mine construction had to ensure the caribou would continue to migrate, which meant preserving all vegetation and ensuring their safe passage through the mining areas.

Today, Canada is the world’s fourth-largest diamond-producing nation. Ekati opened in 1998, followed by Diavik five years later and Snap Lake another five years after that − all within 50 miles of each other. A fourth, Gahcho Kue, will open next year. These, plus the Victor mine in northern Ontario, yielded over 12 million carats in 2014, valued at just over $2 billion.

Exploration teams continue to traverse the northern wilderness. Two mines are under construction elsewhere in Canada, at Fort à la Corne in Saskatchewan and Renard in Quebec, and there are other sites under evaluation.

	The long Arctic winters bring seven to eight months of white landscapes and frozen lakes. The Diavik Diamond Mine, above, is in a kimberlite cluster around frozen Lac de Gras. Photo courtesy Rio Tinto
For all of the difficulties the extreme winter brings, it also presents opportunity. There are no roads beyond Yellowknife, which lies about 200 miles south of the kimberlites. In the deepest of winter, the lakes freeze hard enough to construct an ice highway that heavy trucks use to resupply the mines for the entire year – the difficulties and dangers the ice road truckers face have been well-documented.

The dangers of just being out in this unforgiving winter climate are well known, and the diamond mines have strict rules about employees venturing out in winter. No one can leave their work area without a buddy or go outside during a whiteout blizzard, because people can quickly become disoriented and die from exposure only a few yards away from safety.

“It can happen like that,” said one supervisor at Diavik, snapping his fingers. Source: GIA @topic:7


Title: Fancy Color Diamonds Highlight Alrosa Hong Kong Tender Abstract: This 54.2 ct. Fancy Deep yellow diamond was expected to sell for $1.5 million at the Alrosa diamond tender in Hong Kong. It was mined at Lomonosov pipe in the extreme northwestern area of Russia. Photo by Russell Shor/GIA

                      Alrosa, the world’s largest diamond producer by volume, lowered prices an average of 10% at its regular September rough diamond sale, but demand for its large colorless diamonds and fancy colors remained strong at the company’s tender auction in Hong Kong.

The company, which mines and markets some 90% of Russia’s diamond production, offered polished stones larger than 5 carats and fancy colored diamonds at the Hong Kong auction. The highlights were a 54.2 carat (ct.) Fancy Deep yellow cut-corner rectangle and a 0.42 ct. Fancy Vivid purple pink. The large yellow had a minimum offer price of $1.5 million, according to Alrosa, and the purple-pink diamond had a per carat reserve of “more than $1.6 million,” one trader said.

Officials from Alrosa said both diamonds were mined in the Archangel region near the country’s border with Finland, some 2,600 miles west of Russia’s traditional diamond producing area of Mirny in Siberia. The Archangel operation, mined by a subsidiary named Severalmaz, is relatively new. It began production at the Lomonosov pipe in a small way in 2005, but a 2014 upgrade quadrupled its capacity to 1.4 million carats yearly. Another nearby pipe, Karpinskogo, also came on line last year, producing 266,000 carats, including fancy colored diamonds.

	This 0.42 ct. Fancy Vivid purple pink diamond offered at the September Alrosa diamond tender was mined at Lomonosov pipe in the extreme northwestern portion of Russia. It was expected to sell for more than $1.6 million per carat. Photo by Russell Shor/GIA
Alrosa officials said most of the diamonds at the sale had solid offers − in contrast to the slow business of the trade show happening in the convention hall several floors below. Alrosa has been running invitation-only tender auctions in tandem with the September Hong Kong Gem and Jewellery Fair, the largest single gathering of diamond traders in the world, since 2007. Last year, the company’s Hong Kong sales totaled $43.2 million, which also included on-going sales of rough and commercial sized polished diamonds.

Alrosa surpassed De Beers as the world’s largest diamond source five years ago and sells the vast majority of its production – 38 million carats last year – in regular sales similar to De Beers’ sights. In addition to its Hong Kong tenders, the company also offers large rough diamonds – 10.8 carats and above − via periodic online auctions.

De Beers remains the leader in value, however, logging rough diamond sales of $7.1 billion in 2014 (on 32.7 million carats) compared to Alrosa’s $3.7 billion.

Alrosa’s third quarter sales fell dramatically from $1 billion in last year’s June-September period to $563 million this year. Prices fell 8% to 10% on average during that same period. Its sales volume plunged from 7.6 million carats in the third quarter of 2014, to 4.9 million carats, according to an Alrosa statement.  By comparison, De Beers said it sold 14 million carats during the first half of the year, a 26% decline from the same period of 2014.

In the first half of the year, Alrosa sold just over $232 million to Gokhran, the Russian government stockpiling agency, instead of selling into the difficult diamond market.  Gokhran holds periodic auctions of its diamond stocks and 2015 sales have been running 45% below last year’s levels. The country’s Ministry of Finance estimates a year-end total of $66 million, compared to $102 million last year. Source: GIA @topic:7


Title: Blue Nile: Higher Diamond Prices Result in Reduced Sales Abstract: Engagement ring sales, which comprise about 55% of online diamond retailer Blue Nile's business, declined 4.6% in the second quarter  of 2014. Photo by Robert Weldon/GIA

	Online diamond retailer Blue Nile CEO Harvey Kantor worried publically at the close of 2013 that consumers were beginning to resist higher diamond prices. And as prices for diamonds have risen this year ‒ especially half-carat to one-carat stones ‒ Blue Nile’s sales have indeed been slowing.

	The company reported that “the diamond price environment” in the second quarter of this year resulted in a 1.3% decline in sales compared to the same period of 2013. While it is not the first sales decline in the company’s 15-year history, this one occurred within a relatively healthy retail environment after years of double-digit growth.

	The largest decline, 4.6%, was in engagement ring sales, while non-engagement ring sales increased 2.6%. Engagement ring sales comprise about 55% of the company’s business.

	Not surprisingly, Blue Nile’s sales declines were concentrated in stones smaller than one carat, a segment that had risen in price as much as 10% this year. Sales of larger diamonds, although a small part of the company’s revenue, actually increased because prices for these goods are relatively stable.

	Beyond diamond price increases, Blue Nile is facing strong competition from traditional jewelers building their online presence. So much so, that the company is toying with the idea of going brick-and-mortar – or at least brick-and-boutique.

	Blue Nile has set up trial boutiques in The Wedding Suites areas of two Nordstrom’s department stores, one in the Seattle area and one in suburban New York. Prospective buyers can look at and handle the diamond jewelry, but purchases are still completed online via an onsite computer or the customers’ mobile phones.

	The idea, Kantor said, was to increase the “conversion rate” (clicks to sales), particularly among consumers who check Blue Nile before going shopping for a diamond ring at retail jewelers.

	Blue Nile still anticipates an increase in sales for the calendar year, estimating between $475 and $490 million, compared to $450 million in 2013. That total represented a 12.5% increase from the previous year.

	The company hinted that it will resist further diamond price increases, which will increase the pressure of diamond manufacturers’ bottom lines, even as rough prices continue to climb.

	De Beers hiked prices an average of 2-3% at its July sight on medium quality rough that polishes to less than one carat – exactly the same goods Blue Nile claims are meeting consumer resistance. Source: GIA @topic:8


Title: Online Diamond Sales 17% of U.S. Market; New Auction Records Abstract: The “Imperial Kashmir,” a 17.16 ct sapphire, achieved a world record for a sapphire when it sold for $236,404 per carat ($4.01 million) at a Sotheby’s Oct. 7 auction in Hong Kong. All photos courtesy Sotheby’s

                      A recent De Beers study reported that worldwide retail sales of diamond jewelry totaled $79 billion last year; up $5 billion on a 7% increase in U.S. demand and 12% increase in China.

Online sales of diamond jewelry comprise about 17% of the market in the U.S., according to the study. These sales include both strictly online companies such as Blue Nile, as well as traditional retailers who also sell over the Internet.

The De Beers report also noted that 25% of Chinese consumers now research prospective diamond purchases online before making an actual purchase and that the number of retail stores selling diamond jewelry increased 30% from 2010 to 2013. There are, however, strong signs that the heady growth continues to slow, according to De Beers. Retailers in Guangdong Province reported that sales declined 5.1% for the first eight months of the year, while sales of gold pieces nationwide fell 9.1% during that period, according to a government report.

In the U.S., the Department of Commerce reported that jewelry and watch sales from all sales channels increased 4.9% in August, compared to the same month in 2013. This rise reflects even greater sales volume because prices for gold and diamonds declined several percentage points in this year.

De Beers’ noted that diamond production increased 7% to 145 million carats, still well under the 2005 peak of 175 million carats. It also predicts that production will decline, despite new sources coming on stream, because older mine deposits are getting more costly to work as operations go deeper and ore-grade declines.

De Beers’ Oct. 6 – 10 sightis estimated at $465 million, much smaller than previous sights. The October sight is usually small because it comes just before Diwali, which begins Oct. 20.

Indian diamond manufacturers typically take a two-to-three week break in operations and diamond firms settle their accounts for the year during Diwali. This year, some companies have reportedly offered discounts up to 10% on some slower-moving polished goods to enable them to settle with banks that are cutting back on credit or, in the case of the Antwerp Diamond Bank (ADB), closing doors and calling in loans. The Gem and Jewellery Export Promotion Council, India’s largest industry organization, has denied reports of heavy discounting, saying the long-term prospects for the country’s diamond trade “remain robust.”

ADB has a loan portfolio of $1.6 billion – with nearly all of those clients located in Antwerp. However, 60% of that portfolio is held by Indian firms with roots in Mumbai and Surat. Clients reportedly have one year to close their debts to the bank.

Immediately after the ABD news hit, the Indian Branch of Standard Chartered Bank reportedly informed clients that is was further reducing its financial exposure to the diamond industry and insisting on increased collateral to secure credit lines.

Rough prices have been softening in recent months because of the tightening credit and price resistance in the polished market. De Beers lowered prices very slightly on some high quality goods at the past sight, but prices from other producers sold at tender sales have reportedly fallen by 7%.

AUCTIONS: The records for prices keep breaking as the world’s ultra-wealthy buyers vie for rare, important gemstones. At Sotheby’s Oct. 7 Hong Kong auction, an 8.41 ct GIA-graded Fancy Vivid purple-pink, Internally Flawless diamond drew a winning bid of $17,768,041 from a private buyer from Asia. It was the highest price ever paid for a Vivid pink diamond at auction and, at $2.1 million per carat, it came close to besting the all-time per-carat price achieved by a gemstone.

	A GIA-graded pear shaped Fancy Vivid purple-pink diamond weighing 8.41 cts sold for more than $17.7 million at the Sotheby’s Oct. 7 auction.
The record pre-carat price for a Kashmir sapphire was broken twice at the same sale, the second time within minutes of the first.

The first lot was a 12.0 ct step cut mounted by Cartier, which drew a final price of $2.32 million or $193,975 per carat, besting the record set last year by just over $13,000. A few lots later, however, an Asian collector paid $4.01 million for the 17.16 ct “Imperial Kashmir.” At $236,404 per carat, it easily topped the price mark that had just been set.

While the Intense purple-pink set a record for a diamond of that grade, a pink diamond, graded Fancy Intense by GIA that weighed 24.78 cts, holds the record price for any gemstone, selling for $46 million in 2010.

	This 12.0 ct step cut sapphire and platinum ring by Cartier set with emeralds and diamonds sold for $2.32 million at the Oct. 7 Sotheby’s auction. It briefly set a record at $193,975 per carat until it was surpassed by the “Imperial Kashmir.” Source: GIA @topic:8


Title: Strong Color Zoning Reflects Complex Growth Environment Abstract: Figure 1. The strong color zoning in this Fancy Dark orangy brown diamond was visible at 10× magnification. Photo by Troy Ardon.

			A 2.08 ct emerald-cut diamond recently submitted to the Carlsbad laboratory received a color grade of Fancy Dark orangy brown. Its strong color zoning, visible without magnification, consisted of a dark orangy brown section with a few near-colorless bands and a near-colorless area. The orangy brown section showed numerous very small oriented reflective inclusions, visible in figure 1 only as dark clouds, that are typically associated with type IaA diamonds colored by 480 nm visible absorption bands. Both the near-colorless side and the colorless bands displayed very few oriented reflective inclusions.

				Figure 2. Under long-wave UV illumination at 10× magnification, the diamond’s color zones showed blue and yellowish fluorescence. Photo by Troy Ardon.

				The diamond’s unusual fluorescence under both long- and short-wave UV illumination can be seen in figures 2 and 3, respectively. Under long-wave UV (handheld lamp) the near-colorless section showed typical blue fluorescence. The orangy brown section displayed a yellowish fluorescence, which is common in type IaA yellow diamonds. Under the higher-energy, shorter-wavelength UV excitation of the DiamondView, the distinction between the colors became even more pronounced, and the blue fluorescence of the near-colorless bands was clearly visible within the yellowish green fluorescence of the orangy brown section. Yellow phosphorescence, common in type IaA diamonds colored by 480 nm visible absorption bands, was also observed in the orangy brown area.

				Figure 3. This DiamondView image of the color-zoned diamond shows an even more pronounced distinction between the colors. Image by Troy Ardon.

				Infrared spectroscopy revealed a type Ia diamond with both A and B aggregates. When IR spectra were collected separately from the near-colorless and orangy brown sections, distinct differences were noted. The orangy brown section contained ~33 ppm of A-aggregated nitrogen and ~15 ppm of B-aggregated nitrogen, whereas the near-colorless section showed significantly higher concentrations: approximately 139 ppm of A aggregates and 100 ppm of B aggregates. In addition to the higher overall nitrogen content, the near-colorless portion contained a higher proportion of B-aggregated nitrogen impurities.

				The unique zoning observed in this diamond likely reflects changing conditions during growth. Variations in nitrogen and possibly oxygen content in the earth’s interior—480 nm defects are reportedly related to oxygen impurities in diamond—could have produced the noteworthy color and fluorescence zoning that reveal the complex growth history. Source: GIA @topic:4


Title: Obtaining U.S. Copyright Registration for the Elara Square Cut-Cornered Brilliant Diamond Abstract: In 2000, the U.S. Copyright Office granted what is believed to be the first copyright registration covering a gemstone design. Previously, the Copyright Office maintained that cut designs lacked artistic or sculptural authorship, and that gemstone faceting was a non-copyrightable array of common geometrical shapes in a three-dimensional object. The application to obtain copyright registration for the Elara—a square cut-cornered brilliant diamond design—was initially rejected on similar grounds. However, the position of the copyright examiner was successfully appealed to the highest level of the Copyright Office, which ultimately decided that copyright registration for the Elara cut was appropriate. This experience shows that there may be a new intellectual property vehicle available for manufacturers to protect proprietary cut designs. Source: GIA @topic:7


Title: Spectroscopic Evidence of GE POL HPHT-Treated Natural Type IIA Diamonds Abstract: Results from spectroscopic analyses of GE POL high-pressure high-temperature (HPHT) annealed nominally type IIa diamonds are presented, and these spectral characteristics are compared with those of untreated diamonds of similar appearance and type. Absorption spectroscopy reveals that any yellow coloration in such HPHT-treated diamonds is due to low concentrations of single nitrogen, which have not been observed in untreated type IIa diamonds. Laser-excited photoluminescence spectroscopy reveals the presence of nitrogen-vacancy centers in most, but not all, HPHT-treated stones. When these centers are present, the ratio of the 575:637 nm luminescence intensities offers a potential means of separating HPHT-treated from untreated type IIa diamonds. The total absence of luminescence may be another important indicator of HPHT treatment. Source: GIA @topic:4


Title: “Fluorescence Cage”: Visual Identification of HPHT-Treated Type I Diamonds Abstract: HPHT-treated type I diamonds of various colors may exhibit unusually intense fluorescence at the facet edges and junctions. This effect, here named the “fluorescence cage,” is observed with a fluorescence microscope as a luminous network on the diamond’s surface. It was not observed in untreated diamonds or colorless type IIa HPHT-treated diamonds. This fluorescence pattern is believed to result from a high concentration of HPHT-induced optical centers, which remain on facet edges after repolishing. Source: GIA @topic:4


Title: Clues to the Process Used by General Electric to Enhance the GE POL Diamonds Abstract: The specific details of the process used to enhance color and clarity in GE POL diamonds have not been disclosed. However, a survey of U.S. patents and European patent applications reveals that General Electric has developed a variety of high-temperature annealing techniques at different pressures for enhancing the optical properties of polycrystalline synthetic diamond films and single-crystal synthetic diamond. These methods may provide important clues to the process being used to decolorize natural type IIa (GE POL) diamonds, that is, by reducing the structural defects associated with their brown coloration. Source: GIA @topic:4


Title: De Beers Natural versus Synthetic Diamond Verification Instruments Abstract: Two instruments have been developed at De Beers DTC Research Centre, Maidenhead, to distinguish synthetic diamonds from natural diamonds. The DiamondSureTM enables the rapid examination of large numbers of polished diamonds, both loose and set in jewelry. Automatically and with high sensitivity, this instrument detects the presence of the 415 nm optical absorption line, which is found in the vast majority of natural diamonds but not in synthetic diamonds. Those stones in which this line is detected are "passed" by the instrument, and those in which it is not detected are "referred for further tests." The DiamondViewTM produces a fluorescence image of the surface of a polished diamond, from which the growth structure of the stone may be determined. On the basis of this fluorescence pattern—which is quite different for natural as compared to synthetic diamonds—the trained operator can positively identify whether a diamond is natural or synthetic. Source: GIA @topic:4


Title: Two Near-Colorless General Electric Type-IIA Synthetic Diamond Crystals Abstract: Gemological examination of two near-colorless, isotopically pure, carbon-12 synthetic diamonds grown recently by General Electric reveals short-wave ultraviolet luminescence behavior, a cathodoluminescence pattern, and small metallic inclusions that are typical of other gem-quality synthetic diamonds. These characteristics also help separate them from natural type-IIa diamonds. Study of additional near-colorless synthetic diamonds is needed to confirm these preliminary observations. Source: GIA @topic:4


Title: Two Treated-Color Synthetic Red Diamonds Seen in the Trade Abstract: Two dark brownish red faceted stones, recently submitted to the GIA Gem Trade Laboratory for standard origin-of-color reports, were found to be treated synthetic diamonds. This conclusion was based on observations of: patterns of zoned color, U. V. luminescence, and graining; metallic inclusions; and certain bands in the visible- and infrared-range absorption spectra. We believe that this is one of the first published reports of treated-color synthetic diamonds seen as faceted gems. For some of the gemological features described here, such as visible-range spectra with sharp absorption bands, this is one of the first reported occurrences in gem-quality synthetic diamonds. Source: GIA @topic:4


Title: Age, Origin, and Emplacement of Diamonds: Scientific Advances in the Last Decade Abstract: Scientific advances in the past decade have completely altered our understanding of certain concepts relating to the age and origin of diamonds. As a generalization, most diamonds formed more than 990 million years ago, deep within the earth, from either of two rock types, peridotite and eclogite. They were stored below the base of cratons for varying periods of time, some as long as 3,200 million years, before being transported to the surface. Kimberlite and lamproite, the two rock types usually associated with diamonds, are only the mechanisms that brought diamonds to the surface and are in no way related to the formation of most diamonds. Other topics that are somewhat more speculative, for example, the source of carbon for the crystallization of diamonds and the mechanism of kimberlite and lamproite emplacement, are also discussed and the latest concepts presented. Source: GIA @topic:4


Title: Identification of Synthetic Diamond Grown Using Chemical Vapor Deposition (CVD) Abstract: Studies carried out at the DTC Research Centre have shown that single-crystal CVD synthetic diamond is clearly distinguishable from natural diamond. This article presents information about the CVD process, the history of its development, the different kinds of CVD synthetic diamond material that can be produced, and properties that differentiate them from natural diamond. The authors studied more than a thousand CVD synthetic diamond samples that were grown for research purposes using a range of different process conditions. Absorption, photoluminescence, and cathodoluminescence spectra of these CVD synthetic diamond samples showed a range of different impurity-related features not seen in natural diamond. Photoluminescence imaging is also useful in identifying CVD synthetic diamond, and X-ray topography may give supportive evidence. The effectiveness of the Diamond Trading Company Diamond Verification Instruments for identifying CVD synthetic diamond is also described. Source: GIA @topic:4


Title: Modeling the Appearance of the Round Brilliant Cut Diamond: An Analysis of Fire, and More about Brilliance Abstract: This article presents the latest results of GIA’s research on the interaction of light with fully faceted colorless symmetrical round brilliant cut diamonds of various proportions. The second major article in this three-dimensional modeling study, it deals with fire—the visible extent of light dispersed into spectral colors. As fire is best seen with directed (spot) lighting, the metric for fire presented (dispersed colored light return, or DCLR) uses this lighting condition. DCLR values were computed for more than 26,000 combinations of round brilliant proportions. In general, different sets of proportions maximize DCLR and WLR (weighted light return, our metric for brilliance), but there are some proportion combinations that produce above-average values of both metrics. Analysis of these metric values with variations of five proportion parameters demonstrated that every facet contributes to the appearance of a round brilliant diamond. In particular, star and lower-girdle facet lengths—which are ignored by most cut-evaluation systems—could have a noticeable effect on WLR and DCLR. Observations of actual diamonds corroborate these results. Source: GIA @topic:4


Title: Modeling the Appearance of the Round Brilliant Cut Diamond: An Analysis of Brilliance Abstract: Of the “four C’s,” cut has historically been the most complex to understand and assess. This article presents a three-dimensional mathematical model to study the interaction of light with a fully faceted, colorless, symmetrical round-brilliant-cut diamond. With this model, one can analyze how various appearance factors (brilliance, fire, and scintillation) depend on proportions. The model generates images and a numerical measurement of the optical efficiency of the round brilliant—called weighted light return (WLR)—which approximates overall brilliance. This article examines how WLR values change with variations in cut proportions, in particular crown angle, pavilion angle, and table size. The results of this study suggest that there are many combinations of proportions with equal or higher WLR than “Ideal” cuts. In addition, they do not support analyzing cut by examining each proportion parameter independently. However, because brilliance is just one aspect of the appearance of a faceted diamond, ongoing research will investigate the added effects of fire and scintillation. Source: GIA @topic:4


Title: Exploring the Origin and Nature of Luminescent Regions in CVD Synthetic Diamond Abstract: In the DiamondView instrument, blue to blue-green luminescent zones may be seen in CVD synthetic diamond when the growth run has been interrupted and resumed, a well-known practice in the production of gem-quality CVD synthetics. DiamondView, photoluminescence (PL), and cathodoluminescence (CL) imaging were applied to study the origin and nature of these luminescent regions in two samples of high-purity single-crystal CVD synthetic diamond. DiamondView and PL measurements showed a correlation with silicon-related centers. In addition, CL analysis confirmed the presence of boron. Both silicon and boron showed preferential incorporation at the interface between CVD layers, where a higher uptake of impurities lead to the observed luminescence. Although the growth interruptions cannot be detected with the naked eye, the growth history can be determined accurately using luminescence imaging and spectroscopy techniques. Source: GIA @topic:4


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

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

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

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

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

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


Title: The Cullinan Diamond Centennial: A History and Gemological Analysis Of Cullinans I And II Abstract: The year 2005 marked a century since the discovery of the largest gem diamond ever found: the 3,106 ct Cullinan. Eight decades after it was mined, a team of gemologists conducted the first modern examinations of the two largest diamonds cut from the rough, the 530 ct Cullinan I and the 317 ct Cullinan II, which have been part of the Crown Jewels of England since their presentation to King Edward VII in 1908. This article traces the history of this famous piece of rough and its source, South Africa’s Cullinan (formerly Premier) mine, which has yielded more significant diamonds than any other single locality. It also presents the full details of the examination and grading of these two approximately D-color, potentially flawless historic diamonds. Source: GIA @topic:7