FAKE AND ALTERED DIAMONDS
Zirconia special color
Materials sometimes passed off as diamonds include synthetic white spinels and sapphires, zircon, strontium titanate, synthetic rutile and yttrium aluminum garnet (YAG). Most fake diamonds such as those made from cubic zirconia are easy for gemologists to spot.
A laboratory-grown crystal called moissanite looks so much like diamonds that even jewelers have been fooled. YAG, the stone featured in the Wellington jewel ads, is also very similar to a diamond. The easiest way to tell YAG from a real diamond is to immerse it in mineral oil. Because the chemical composition of YAG is almost the same as oil it facets seem to disappear in the oil while those of real diamond remain sharp and sparkling. Diamonds are used in cataract surgery on blades that cuts without tearing.
Buyers should be on the alert when buying a diamond. Sellers often try to sell customers diamond that have been altered or enhanced. Lasers are sometimes used to burn holes into diamonds to remove dark spots and inclusions which lessen a stone’s value. The holes are then filled with acid which bleached the imperfection and creates an illusion of flawlessness. Blemish and cracks can be masked by a type of molten glass that refracts light on the same way a diamond does. These alteration are often temporary and are easy to detect.
Colored diamonds are rare in nature. Irradiation and a combination of heat and pressure can transform a natural white diamond or a synthetic diamond into a colored diamond or change a brown diamond of low value into a valuable "colorless" stones. Trained gemologists can usually detect such alterations.
Zirconia CZ brilliant Websites and Resources on Gems: All About Gemstones allaboutgemstones.com ; Minerals and Gemstone Kingdom minerals.net ; International Gem Society gemsociety.org ; Wikipedia article Wikipedia ; Gemstones Guide gemstones-guide.com ; Gemological Institute of America gia.edu ; Mineralogy Database
webmineral.com ;
Websites and Resources Diamonds: Info-Diamond info-diamond.com ; Diamond Facts diamondfacts.org/about/index ; Diamond Mining and Geology khulsey.com/jewelry/kh_jewelry_diamond_mining ; Diamond Mine mining-technology.com/projects/de_beers ; Costellos.com costellos.com.au/diamonds ; DeeBeers debeers.com/page/home/ ; Wikipedia article
Wikipedia ; American Museum of natural History amnh.org/exhibitions/diamonds ;
Book: The Heartless Stone: A Journey Through the World of Diamonds, Deceit and Desire by Tom Zoellner.
Synthetic Diamonds
Irrdiamond specimens Synthetic diamonds are generally made by compressing graphite under pressure of one million pounds per square inch while the material is heated from 2500 degrees F to 3500 degrees F—roughly duplicated conditions deep in the earth that create natural diamonds. The process was invented by General Electric in 1954 and the diamonds produced are about a half a millimeter in size. Most synthetics show a distinctive patterns when viewed under ultraviolet light. <>
The first synthetic diamonds were made in the 1950s. were so tiny they were more like diamond dirt. Producing synthetic diamonds for cutting tools, optical equipment and lasers is now easy and common-place enough that there are thousands of small plants in China producing them. [Sources” Alice Park, Time, February 12, 2007, Urlich Boser, Smithsonian magazine, June 2008]
Producing gem-quality diamonds of a carat or larger is a far more difficulty endeavor. But the process has slowly improved over the years to a point where it is now possible to grow rough diamond stones than can be cut and polished into gems over a carat in size. As of 2008, the latest single-crystal diamond grown in a lab was 15 carats, or about 0.7 inches by 0.2 inches. A synthetic diamond placed in a high-pressure, high-temperature furnace at the Carnegie Institution’s Geophysical Lab that changed its atomic structure was so hard it broke a hardness gauge itself made from diamonds and endured pressures five million times greater than the atmospheric pressure at sea level.
Great Mogul Diamond copy Apollo Diamond is leader in the synthetic diamond trade. Based in a secret location in a Boston suburb, it has made such advances that its executives fear for their own safety. The company is run by a father and son team: Robert and Bryant Linares. Robert began his career in crystal synthesis research at Bell Labs and later started a semiconductor company that he sold too get money to bankroll his dream of creating synthetic diamonds. Through trial and error, using equipment set up in his garage, he worked out the precise combination of gases and heat to grow large crystal diamonds.
Even DeBeers has entered the synthetic diamond business, with a division called Element Six, which has produced diamond wafers up to six inches across.
DeBeers sells two machines that can distinguish between natural diamonds and synthetic ones. The machines detect chemical and structural characteristics that sometimes vary between natural diamonds and synthetic ones, but neither machine can tell the difference all time. The best way to determine whether a diamond is natural or synthetic is to cool it with liquid nitrogen and then shoot a laser through it to see how light behaves when it passes through it, the process is expensive and takes several hours.
Takashi Hagiwara wrote in the Yomiuri Shimbun: “Artificial diamonds are most commonly produced by decomposing methane gas in a microwave oven at temperatures of about 1,000 C. This process produces minute flakes of carbon, which pile up like accumulated snow to form a thin layer, or laminate, of diamond.” [Source:Takashi Hagiwara, Yomiuri Shimbun, October 17, 2010]
Estimated World Production of Synthetic Diamond, By Country (Thousand carats): 1) United States 258,000; 2) Russian Federation 80,000; 3) South Africa 60,000; 4) Ireland 60,000; 5) Japan 34,000; 6) Belarus 25,000; 7) Sweden 20,000; 8) China 18,000; 9) Ukraine 8,000; 10) France 3,000 [Source: United States Geological Survey (USGS) Minerals Resources Program]
Making Synthetic Diamonds
Great Star of Africa copy Apollo, Element Six and most other diamond makers rely on a process called chemical vapor deposition (CVD) to make synthetic diamonds. The process utilized high temperatures (1,800 degrees F) but relatively low pressures in a vacuum chamber to heat a plasma that crystalizes atom by atom into seed which grows a large single-crystal diamond over the course of a few weeks.
Under the CVD method: 1) methane and hydrogen gas are channeled through a chamber containing diamond seed slivers, 2) heat is applied, and a complex chemical reaction causes the methane to slough off its hydrogen atoms; 3) the remaining carbon deposits itself atom by atom as diamond onto the diamond-seed slivers.
Apollo uses washing-machine-size reactors covered with tubes and gauges to makes its synthetic diamonds. The seeds take two to four weeks to grow. Describing the diamond-growing area of the Apollo Diamond laboratory Alice Park wrote in Time, “Peer through a window of one of Apollo Diamond’s canister-like reactors...The inside of the cramped chamber is bathed in a magenta glow...Evenly arrayed on a small platter at the center of this colorful haze are what look like 16 lozenges burning with an even deeper pink hue...each of these small pinkish disks is a diamond, growing from a tiny seed crystal.”
Other companies make diamonds using the High Pressure, High Temperatures (HPHT) method, the tried-and-true method which was used to make the first synthetic diamonds. HPHT mimics the diamond-making process in the middle of the earth with heat of about 2,000 degrees F and pressure many of times greater than that on the surface of the Earth generated in a washing-machine-size device. Relatively large amounts of nitrogen are used, which turns the diamonds an amber color. Stones larger than six carats are hard to make using this method. The one advantage HPHT has over CVD is cost. It is much cheaper than even natural stones, A Florida-based company called Gemesis sells one carat synthetic amber diamonds for about $6,000, compared to $20,000 for the same size natural amber diamond.
Synthetic Diamond Jewelry
Lesser Star of Africa copy Apollo is already producing CVD diamonds for the jewelry market. In 2006 it started selling rough gems to a Boston jewelry retailer. A company called Staur sells a necklace made with two-carat synthetic diamonds for $129. The company claims the diamonds are the same quality and size of those on a $20,000 necklace made with natural diamonds.
Synthetic diamonds can be produced in a variety of colors, shapes and sizes. As of 2008, Apollo’s large colorless diamonds sold for around the same price a natural diamonds the same size. It’s pink, blue, champagne, mocha and brown diamonds go for about 15 percent less than natural stones of the same color, which are rarer and more expensive than white diamonds.
In 2007, the Gemological Institute of America, a leading grader of diamonds, agreed to rate synthetic diamonds using the same four C’s—carat, cut, color and clarity—as it does witj natural diamonds. One jeweler who examined a synthetic stone produced by Apollo told Smithsonian magazine, “There’s no way to tell that it’s lab created.”
No one wants synthetic diamonds to be marketed too cheap, causing the diamond industry to collapse. On competition from synthetic diamonds, a spokesman for DeBeers told Smithsonian magazine, “Diamonds are rare and special things with an inherent value that does not exist in factory-made synthetics. When people want to celebrate a unique relationships they want a unique diamond, not a three-day-old factory-made stone.” Some synthetic diamond producers was to call their products “cultured diamonds.” The Jewelers Vigilance Committee (JVC), a trade group, is lobbying hard to prevent use of that term. “Cultured” is a term used in the pearl business.
Applications of Synthetic Diamonds
Will they one day make these
(the British Crown Jewels) with synthetic gems? Diamonds have a number of unique qualities that makers them ideal materials for much more than just jewelry and cutting tools. Because they conduct heat so well they hold great promise for advancing the electronics industry and are especially useful making a new generation of processors that don’t generate large amounts of heat like silicon ones do. This application alone paves the way for super-thin laptops, wristwatch-size cell phones and digital recording devises that hold thousands of movies in a palm-size device. Another advantage that diamonds have over silicon is that they are stronger and don’t break down at high heats. Silicon is currently the primary material used to make processors and semiconductor.
Diamond’s ability to dissipate heat also has applications for things like sophisticated lasers and the windows of spacecraft, protecting them during launching and returning into the atmosphere. The U.S. Navy is studying the use of diamonds in next-generation grid switches, as a wear-resistant coating for military equipments and as a material to use in biological weapon detectors.
Biologists are attracted by diamond’s inertness—the fact that it doesn’t react with any substance and doesn’t degrade even when doused in powerful natural acids and other chemicals found in the body. One application being studied is a diamond-based electrode that could be designed to react chemically to certain proteins.
Apollo grows CVD diamond wafers that are large enough and of a quality that makes them useful in the electronics industry. CVD produces uniform, consistent diamonds that, for example, can be used as effective transistors and semiconductors. Apollo’s president Bryant Linares told Time , “You need to make other seeds that will allow you to control the end product. For semiconductor manufacturing, that means an extremely smooth and flat surface. For the first time we’ve done that.” Apollo is currently working on high-quality diamond slivers that can be marketed comedically. The main drawback with diamond semiconductors—one that will take some time to overcome—is the high cost of producing them.
Diamond Semiconductors
Takashi Hagiwara wrote in the Yomiuri Shimbun: “The artificial diamond super semiconductor is being developed by the Diamond Research Laboratory of the National Institute of Advanced Industrial Science and Technology (AIST). The AIST team has found a way to accelerate the diamond laminating process, and can efficiently produce diamond laminates measuring 2.3 centimeters square and 0.4 millimeter thick--a size that ranks alongside the largest artificial diamonds produced. [Source: Takashi Hagiwara, Yomiuri Shimbun, October 17, 2010]
“While diamond has natural insulating qualities, adding minute amounts of boric acid and some other substances during the methane-decomposition process produces diamond that also acts as an excellent semiconductor. The resulting substance is described by the AIST team as "the ultimate insulator," far excelling silicon in terms of thermal radiation and voltage resistance. "Given that artificial diamonds can be produced from carbon, which is obtainable in abundance, the diamond semiconductors we envision would be well suited to mass production," said Shinichi Shikata, 56, who heads the AIST team. He joined AIST after quitting a managerial post with a diamond-processing company six years ago. Shikata and his team foresee diamond semiconductors being used in electric vehicles and gas-electric hybrids. [Ibid]
“Silicon semiconductors require a cooling system to prevent malfunction due to overheating. This is not true of diamond semiconductors, Shikata said, because of diamond's heat-transferal efficiency. The AIST team last year created a prototype semiconductor element measuring 1.6 centimeters square, incorporating a 3 square-millimeter diamond semiconductor. If about 10 such elements were combined to form one large element, it would be suitable for use in the power control system of a hybrid vehicle, Shikata said. [Ibid]
“A hybrid car equipped with such technology would consume about 960 kilowatt hours less per year than a conventional hybrid. If every hybrid vehicle currently in use worldwide had such a system in place, their collective carbon dioxide emissions would be reduced by about 5 million tons over 40 years, he said. "Our goal is for diamond elements to be in practical use within 10 to 15 years," he said. "If mass-produced, their production cost would be comparable to that of silicon-based elements." "We'd like to see diamond semiconductors become commonplace some day, since they would be sure to help realize a low-carbon society," he said. [Ibid]
“Shikata's laboratory also has been pursuing research into developing high-performance transistors with artificial diamonds. By manipulating the elemental composition of the carbon flakes, the resulting artificial diamond's heat conductivity can be increased by 150 percent, and have the ability to latch on to electrons, Shikata said. "We can apply this phenomenon to the production of a high-performance transistor," he said. [Ibid]
Image Sources: Wikimedia Commons
Text Sources: New York Times, Washington Post, Los Angeles Times, Times of London, The Guardian, National Geographic, The New Yorker, Time, Newsweek, Reuters, AP, AFP, Wall Street Journal, The Atlantic Monthly, The Economist, Global Viewpoint (Christian Science Monitor), Foreign Policy, Wikipedia, BBC, CNN, NBC News, Fox News and various books and other publications.
© 2008 Jeffrey Hays
Last updated August 2012