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Formed Underground or in a Lab: Diamonds Still Sparkle

Thinking about a diamond for your valentine? How about one made by scientists? 

General Electric announced in 1955 that its scientists had created a diamond. Although man-made, the synthetic diamond was pure carbon, just like a natural diamond. The company didn't enter the jewelry business but “used the stones to make tools for cutting and polishing metals, glass and even teeth,” according to GE Reports, a company newsletter.

Synthetic diamonds recently have caught the attention of members of the jewelry business, including Joe Cheslock, owner of Sycamore Jewelers in Midlothian. “Synthetic diamonds have the same chemical, physical and optical properties as natural diamonds but are grown in a lab,” Cheslock said. Imitation diamonds, like cubic zirconia, “may look like natural diamonds but aren't made of the same material,” he said. Sycamore Jewelers is not currently stocking synthetic diamonds, but Cheslock said he is following the trend closely.

Natural diamonds were formed one to three billion years ago deep within the earth. Carbon deposits were squeezed under extremely high pressures and temperatures, causing the carbon atoms to bond so tightly that they formed crystals of the hardest substance known. Diamonds were formed so deep in the ground that humans wouldn't know about them if volcanic eruptions hadn’t brought diamonds closer to the surface where they could be mined. Natural diamonds are mined in several African countries, especially South Africa, and in Australia, Russia and to a lesser extent, in Canada, according to Cheslock. Very few diamond deposits are known in the United States.

Several synthetic diamond manufacturers supply the jewelry industry, Cheslock said. Most of these diamonds are made either with a process called chemical vapor displacement (CVD) or with high temperature-high pressure (HPHT). Both start with a tiny seed of natural diamond to speed up the process.

In HPHT, the diamond seed is placed in a press, along with graphite, a form of carbon, and heated to about 1400 C (2550 F) under high pressure. This process is the closest to the way natural diamonds formed below the earth. HPHT also is used to enhance the color and clarity of natural diamonds. CVD also starts with a seed diamond but does not use high pressure. In fact, the chamber in which the diamond is grown is depressurized. A microwave beam is directed at methane gas that has been heated to about 2000 degrees C (3600 F). Carbon atoms from the methane adhere to the diamond seed, gradually building up a synthetic diamond.

Making a synthetic diamond can take days or weeks, depending on the manufacturing process and size of the diamond. “Detection of synthetic diamonds is very difficult,” Cheslock said, but equipment is now available to make the job easier and more reliable. On average, synthetic diamonds cost about 15 to 20 percent less than natural diamonds, according to Cheslock.

Cheslock’s partner, Terry Sprankle, said he doesn’t feel that the current price difference is enough to sway most buyers toward a synthetic, but that probably will change. However, he said, “Synthetic diamonds are eco-friendly and that may influence some buyers, especially millennials.”

Diamond mining has come under considerable criticism for environmental and labor practices, safety and other concerns. Efforts are under way to improve mining operations worldwide to ensure that “diamonds are ethically sourced, not used to finance wars or weapons, and that workers are treated fairly,” Cheslock said.

Scientists continue to find new applications for diamonds. Jefferson Labs in Newport News, which is funded by the U.S. Department of Energy, is using diamonds to help detect particles in its atom smasher called a continuous electron beam accelerator facility (CEBAF). The diamonds, roughly 0.02 of an inch thick, are used in place of silicon in computer chips. “If you build a computer chip on a diamond rather than on a silicon wafer, it can be impacted with many, many times more radiation than silicon,” Dipangkar Sutta, a physicist at the Newport News lab, said in a news release, “Nobody has used this kind of detector in physics before.” Researchers at Harvard University's School of Engineering have used a diamond to create the world’s smallest radio receiver. The receiver can withstand harsh environments and is bio-compatible, which means it could be implanted in the human body.

“Diamonds are forever” is a catchy marketing phrase developed in 1947. The slogan continued as the title of a 1971 James Bond spy film. Whether natural or synthetic, the diamond mystique will continue to have a place in jewelry stores and industrial settings, all aided by science and technology.