Gem-quality synthetic diamond

Gemesis, which makes HPHT fancy intense and vivid yellow “cultured” diamonds, provided these matching earrings—pear shapes weighing 1.13 cts. t.w.—and a 1.04-ct. round brilliant center stone. Bottom, a characteristic rough crystal is shown with a .89-ct. princess cut, a .56-ct. round brilliant, and a .95-ct. Asscher cut.

Call it cultured, call it created, call it synthetic. Just don’t call it a substitute, an imitation, or a fake. It’s a real diamond, with the same chemical, physical, and optical properties of the natural, Mother Nature-made variety. The only difference: It was made by science and technology.

History. In the mid-1950s, General Electric’s Tracy Hall Sr. built his first diamond press. Duplicating the Superman hand-squeeze, it compressed elemental carbon with plenty of heat to produce the world’s first synthetic diamond. (Note: GE’s press release on the process is dated Feb. 15, 1955. Swedish scientists claimed they had synthesized diamond a few years earlier, in 1953, but their research apparently went unpublished, and GE established the world patent using Hall’s work.)

The result was industrial-quality diamond. Gem-quality synthetic diamond came a decade later, but it was too expensive to make synthetics and compete with their natural counterparts. So the experiment faded away quietly … in the eyes of jewelers, that is.

On the industrial front, the synthetic diamond business grew large enough to replace natural diamond as the product of choice. A 1993 De Beers report claims that the world consumed 601 million carats of diamond for industrial use. Of that total, 600 million carats were synthetic. (De Beers is world’s largest producer of man-made diamond.)

Then, in 1986, Sumitomo Electric, GE’s Japanese rival, stunned the jewelry industry by creating high-clarity, fancy yellow-colored gem-quality diamond—in commercial quantities, and for less money than the cost of a natural diamond of the same quality.

But the creation of commercially affordable synthetic gem-quality diamond did not spell the doom of the diamond market. Like all other laboratory-grown gems, the Sumitomo diamond soon found its own small niche—those who wanted a fancy yellow diamond but couldn’t afford the natural variety. (While a small amount of Sumitomo-like synthetic yellow diamond did appear in the Los Angeles market in the late 1980s and early 1990s, Sumitomo claims it never sold into the jewelry or gem trade, but rather focused on electronic applications only.)

Today, with even more advances in diamond growth technology, new presses—some created by Tracy Hall’s sons, David and Tracy Hall Jr.—now are manufacturing synthetic gem-quality diamond in a variety of colors.

Origin. Technological advances have given most industrialized countries the ability to synthesize diamond. Commercially available synthetic gem-quality diamond is produced in the United States, Russia, and Japan. China also is forging ahead in this area, with thousands of small shops reportedly in the synthetic diamond business.

Diamond is simply elemental carbon. To make gem-quality synthetic diamond, the carbon must form tight octahedral bonds. It was believed that this could be achieved only by using enormously high heat and pressure. Therefore, the high-pressure, high-temperature (HPHT) process was the driving force behind the creation of synthetic gem-quality diamond. Both GE and Sumitomo Electric had the ability to drive the huge presses that could squeeze carbon into an octahedral bond.

Once HPHT technology became known, it didn’t take long for other laboratories to try to duplicate the process. And many were successful—especially in Russia, where physicists also claim they achieved synthesis prior to 1954. Tom Chatham of Chatham Created Gems in San Francisco made numerous attempts in the 1990s to finance Russian synthetic diamond projects but was left without a commercial product.

In 2003, Chatham’s luck changed. He has since found a reliable and capable source for HPHT-created diamonds and markets them in his line of created gems. On the other side of the United States, General Carter Clarke also looked to Russia. However, instead of trying to work in Russia, he acquired Russian technology and brought it to Florida.

Alex Grizenko of Lucent Diamonds in Golden, Colo., had the advantage of his Russian heritage: He worked out a successful business proposition with Russian manufacturers and has been marketing his Russian product in the United States for the past several years under the Lucent name. Grizenko also has branched out into another origin for synthetic diamond manufacture—using carbon from the cremated remains of loved ones to create diamonds marketed under the name LifeGems. Current HPHT technology can grow rough crystals as large as five carats, and growing time is counted in days, not weeks or months.

As HPHT advanced, chemical vapor deposition (CVD) technology also was being used to make synthetic diamond, only this time as thin films. Unlike HPHT, CVD requires different heat variables and much less pressure. (CVD is formed in a vacuum.) In the CVD process, a cloud of elements hovers over a seed plate. As the cloud hits the right combination of pressure, temperature, and gas composition (a triangulation of properties), it rains elements onto the seed, upon which crystals are grown. If the seed is a group of crystals, multiple crystals grow. If the seed is a single crystal, a single-crystal diamond is grown. Synthetic CVD diamond was developed first as a polycrystalline material in the mid-1990s and was being used for industrial purposes to coat items such as saw blades and drill bits, helping tools resist wear and tear.

A leader in this technology, Apollo Diamond, located in the Boston area, wanted to create gem-quality single crystals. Early in 2003, the company announced its success. The main reason for creating clear tablets of diamond is to make them into computer chips. More immediate use of CVD will be seen in communication devices and photonics as well as semiconductor electronics. An eventual byproduct of this development will be CVD diamond for the jewelry industry. Current technology can be used to grow gem-quality synthetic diamond in sizes large enough to facet .25-ct. to .50-ct. diamonds, in light to dark brown, as well as blue and near colorless varieties.

Colors. Synthetically grown diamond gets its color through the addition of small traces of other elements, such as nitrogen for yellow and boron for blue. Naturally grown colors include the pink and brown range, as well as green, green-blue, and black. Other colors, such as red, are first grown one color, then irradiated or heated to create a final color.

Nitrogen is found in most HPHT-manufactured diamonds, since it makes growth easier. It also makes a diamond yellow, as it does natural diamond. Colorless synthetic diamond could be made, but because it is difficult and expensive to produce, it’s not yet commercially manufactured.

Apollo CVD synthetics are grown near-colorless to brown. Like HPHT synthetics, the addition of boron, instead of nitrogen, will create a blue color.

Quality. Clarity in gem-quality diamonds can range from VVS through I3, depending on the press, the press operator, or the CVD chamber. Most synthetic diamonds offered for sale are classified as VVS through SI. Inclusions are typically white in color, mostly pinpoints, with the exception of metallic iron flux in the HPHT grown material.

Prices. “Less than the price of natural” is the operative comment, but this will vary depending upon the manufacturer or distributor, color, and size of the synthetic diamond.

Enhancements. Diamond, synthetic or natural, can be enhanced using HPHT, irradiation, laser, and fracture fillings. Apollo diamond is grown as Type IIa, which can routinely be enhanced by HPHT. Grown blue HPHT synthetics also are Type IIa, and could also be HPHT processed.

Bench care and cleaning. Synthetic diamond is as durable as the natural product. The usual precautions apply as when working with any diamond.