The technology for producing gem-quality synthetic diamonds is maturing, the producers are willing and consumers are receptive

Synthetic diamond jewelry. Utter these words in the presence of diamond merchants and the result is dissonance. Some embrace the product, some fear it will destroy the industry, some change the subject.

Regardless of your position in this debate, one fact remains constant: synthetic diamond jewelry is as predictable as an increase in rough diamond prices. We can predict it will happen, we just don’t know when.

Why is this product inevitable? Because the pieces are all there: maturing technology, willing producers, receptive consumers.

This year marks the 25th anniversary of General Electric’s first gem-quality synthetic crystals. Sumitomo of Japan has more than a decade of commercial high-quality synthetics production under its belt. And more recently, De Beers Industrial Diamond Division entered the market with its high-quality Monocrystals®. True, Sumitomo and De Beers target their products for industrial application. But the underlying message is unmistakable: high-quality crystal growth can be cost-effective.

General Electric, Sumitomo and De Beers consistently affirm their policies of refraining from selling synthetic diamonds for jewelry use. However, crystal growers in Russia face a different reality: economic survival. It’s not difficult to understand the Russians’ incentive to transform the products of their research into cash in their pockets.

But will consumers embrace synthetic diamond jewelry? A clear answer emerges from the aftermath of an NBC Dateline feature story on this subject: a tidal wave of inquiries to Chatham Created Gems, the San Francisco company involved in a joint venture with the Russian crystal growers. The inquiries came from jewelers and were spurred by customers looking for the promise of (synthetic) diamond jewelry at an extraordinary price point. Couple this response with the current widespread consumer acceptance of synthetic emeralds and rubies, and the evidence points to a friendly reception for man-made diamonds.

Will you be prepared for the first synthetic diamond that crosses your desk? Will you identify it as such? The answers to these questions require a shift in the way we think. We need first to acknowledge the possibility of synthetic origin with every diamond. After that, identification is a relatively straightforward task.

Natural vs. synthetic: Most man-made diamonds have distinguishing characteristics inherited from their synthetic origin. Each specimen may not exhibit all of these characteristics, however. While one diamond may show very obvious indications, such as metallic flux inclusions (remnants of the crystal growth medium), others may require additional inspection and testing to confirm origin.

This article will focus on test results produced with standard gemological equipment. These tests fall into two categories: microscopic examination and ultraviolet testing. You may have read or heard about other characteristics, but they are more applicable to crystals than to faceted stones or require more sophisticated equipment than is generally available.

(A note of caution before we proceed: when in doubt, send the stone to a qualified laboratory for confirmation of origin. A growing body of synthetic diamond test data highlights the unique and differentiating characteristics of today’s products. However, this technology will continue to evolve as manufacturers pursue better, faster, more cost-effective methods of synthesis. This evolution will undoubtedly affect our approach to separating natural from synthetic.)

Here are four indicators of synthetic diamond:

• Microscopic examination/inclusions. Synthetic diamond crystals grow in molten metal flux – usually a nickel-iron mixture. If metallic flux remnants are trapped in the diamond crystal during growth, the resulting inclusions provide evidence of man-made origin (Photo 1). There are no reports of natural diamonds containing this type of metallic inclusion.

• Microscopic examination/color zoning. Although near-colorless synthetic diamonds are the product of choice for jewelry, the majority produced to date are “fancy yellow.” A common attribute is non-uniform distribution of color. This color zoning (Photo 2) appears in regular patterns and follows the internal crystal growth structure. This phenomenon is also evidenced by an unusual response to ultraviolet light, as discussed below.

• Ultraviolet testing – shortwave vs. longwave. The most reliable separation of natural from synthetic diamonds is their response to ultraviolet radiation. But be sure to go beyond the normal ultraviolet “fluorescence” test and check the response to both shortwave and longwave UV. The standard fluorescence response of natural diamonds is stronger to longwave than shortwave. However, many synthetics are inert to longwave and show a distinct response to shortwave. If you test only with longwave UV, you’ll miss this key identification characteristic.

• Ultraviolet testing/irregular fluorescence. Not all natural diamonds fluoresce when exposed to ultraviolet light. Those that do show uniform fluorescence. In synthetic diamonds, however, some areas fluoresce while others remain inert (Photo 3). In the yellow synthetics described above, these fluorescence patterns correspond to the color zoning.

Two key points to remember when checking for ultraviolet response: test with short and longwave, and check for fluorescence characteristics in a dark room after your eyes have adjusted to the darkness.

The process: Diamond formation – whether natural or synthetic – requires extremely high temperature and pressure: 2,500º-2,900ºF and 50-60 kilobars (1.5 million pounds per square inch). Containing and controlling such an extreme environment demands state-of-the-art equipment.

Successful synthesis of large gem-quality crystals mandates even greater complexity; growth must be slow and stringently controlled. General Electric developed a technique called “temperature gradient” that grew the first gem-quality diamond crystals. Figure 1 is a simplification of the diagram published by Dr. Herbert M. Strong, a member of the GE research team.

Figure 1. Schematic of a diamond synthesis vessel.

A carbon nutrient (for example, synthetic diamond grit) and metal-alloy flux are placed in a synthesis vessel. Temperature and pressure are increased until the metal flux is liquefied, which in turn dissolves the carbon nutrient. The vessel is warmer in the center and cooler at the ends where the seed crystals are located. This temperature gradient causes carbon dissolved in the metal flux to “precipitate out” of solution and bond to the seed crystals, resulting in the desired crystal growth. If the growth rate is too fast, spontaneous nucleation retards the growth.

Crystal growers say a 1-ct. gem-quality crystal takes about 45-60 hours to grow (“Growth of Synthetic Diamond,” Burns and Davies). The current published record for the largest synthetic diamond, albeit industrial quality, is a 34.8-ct. crystal grown by De Beers. This particular stone required 600 hours (25 days) to grow.

Flashback – Dec. 16, 1954: “My hands began to tremble, my heart beat rapidly, my knees weakened and no longer gave support. My eyes had caught the flashing light from dozens of tiny triangular faces of octahedral crystals … and I knew that diamonds had finally been made by man” – the historic event as memorialized by Dr. H.T. Hall.

Hall and a small group of scientists and engineers comprised the nucleus of General Electric’s high-pressure diamond project. Their work began in 1951 and was built on Dr. Percy Bridgman’s seminal research. Hall’s modification of Bridgman’s original equipment design culminated in an important breakthrough: a high-temperature, high-pressure vessel that yielded the required environment and delivered the first successful diamond synthesis late in 1954. Refinement of this process led General Electric to market the first commercial synthetic diamond grit in 1957.

Although, it may not seem difficult to advance from small diamond grit to larger high-quality crystals, it was an enormous challenge. Fifteen years of intense research preceded the next dramatic advance. Again it was General Electric that announced the breakthrough production of gem-quality synthetic diamond crystals.

Gems & Gemology, a quarterly publication of the Gemological Institute of America, published reports on the GE research products in 1971 and 1984. The latter issue reported a noteworthy conclusion: “While there has been considerable speculation in the trade that other countries have begun to produce gem-quality synthetic diamonds, many researchers in the U.S. maintain that the large-scale production of gem-quality synthetic diamonds is still not financially feasible.”

A few months later, Sumitomo Electric Industries of Japan dashed wishful speculation.

Then there were three: In April 1985, Sumitomo announced large-scale production of synthetic gem-quality diamond crystals. Reporting the gemological properties of these crystals, GIA researchers left the industry with a solemn warning: “The large-scale production of gem-quality diamonds by Sumitomo Electric Industries forces members of the jewelry industry to reconsider their views regarding the likelihood of such material appearing in the gem marketplace” (Gems & Gemology, Winter 1986).

That prediction came to pass quickly. On Feb. 18, 1987, two diamonds were submitted to GIA’s Gem Trade Lab in New York City for origin-of-color reports. Examination identified one as a natural fancy color diamond, the other as a synthetic – with properties suggesting it was the new Sumitomo product! A Sumitomo spokesman assured the industry his company had no intention of producing synthetics for jewelry use.

Later that year, another G&G report focused on De Beers’ gem-quality synthetics. The article noted that De Beers’ Diamond Research Laboratory had grown gem-quality synthetics on a limited experimental basis since the 1970s. De Beers emphasized it had no plans to market such

products commercially. But plans changed. Industrial Diamond Review reported in its January 1993 issue that “a line of yellow, single-crystal industrial products are being sold under the De Beers Monocrystal® trademark for industrial tools.”

General Electric, Sumitomo and De Beers: three independent confirmations that gem-quality synthetic diamonds had gone beyond the status of laboratory curiosity and into the marketplace.

The Russians make four: Russian scientists actively researched and pursued diamond synthesis for decades at several locations. One report (Mazal U’Bracha, No. 53) indicates their first success with large synthetic crystals was in 1989.

Then in 1991, Russian producers allowed a few members of GIA’s research team to briefly examine three small gem-quality crystals said to have been grown only for experimental purposes. Little did we know then that reports of these little “experiments” were the vanguard of headlines soon to come.

In July 1993, Tom Chatham of Chatham Created Gems stunned the industry with a pronouncement that synthetic diamond jewelry would soon be here. He explained that his company was collaborating with a Siberian crystal grower to produce Chatham Created Diamonds. After the immediate flurry of reports, the topic faded from headline status. Then, television journalists discovered a story.

In April 1995, the promise of synthetic diamond jewelry was aired in a feature story on NBC Dateline. The May issue of JCK reported the event with the following quote from Chatham: “We still need to get the Russian production up to speed to support the demand.” That demand was certainly enhanced by NBC’s enticing price comparison: synthetic diamonds at 10% the price of natural! With television celebrating the virtues of synthetic diamond jewelry, can the actual product be far behind?

Remember that in addition to the Russians, at least three other major companies have the technology to manufacture high-quality synthetic diamonds. Sumitomo, GE and De Beers all have publicly affirmed their commitment to refrain from commercial production of gem-quality synthetic diamonds for jewelry use. But this all underscores an important fact: the technology for producing gem-quality synthetic diamonds is maturing.

A colorful past: On two occasions in 1993, red synthetic diamonds were submitted to GIA’s Gem Trade Laboratory in New York City for routine origin-of-color reports (Gems & Gemology, Fall 1993). Tendered by different clients, the first was a 0.55-ct. round brilliant, described as dark brownish orangy red, while the second was a 0.47-ct. dark brownish red radiant-cut. The next year, GIA’s lab in Santa Monica, Cal., received a small round dark red synthetic diamond for an origin-of-color report (Gems & Gemology, Spring 1995).

GIA identified all three diamonds as synthetics, but with a new twist – their color resulted from artificial radiation! Tests produced results very similar to those observed in Russian-grown synthetics; GIA didn’t speculate on where the stones were treated. But an article appearing in the November 1993 issue of Rapaport Diamond Report provides insight: “At present, Chatham says, he is producing … mostly pale yellows … He has also produced a bright red diamond ‘that looks like a ruby’ – the result of radiation.” (Chatham recently said, however, that “all efforts today are for white stones, with .75 ct. to 1 ct. our goal.”)

Interestingly, the March/April 1994 issue of Diamond International carried a similar comment in an article titled “Russian Synthetics Examined.” The article detailed the results of testing several Russian synthetic diamonds provided by Walter Barshai of Pinky Trading. The article includes the following comment: “The [Russian] producers further revealed that they had produced pink to red synthetic diamonds by irradiating the synthetic yellow stones.”

These two public, almost matter-of-fact, comments regarding the Russians’ ability to produce pink and red diamonds suggest the red diamonds submitted to GTL were synthesized and treated in Russia.

The future now? In 1954, Dr. Hall’s tiny crystals spawned an unforeseen new technology. Four decades later, the real prospect of synthetic gem diamond production sends shivers up the spine of our industry.

Debate on whether they will materialize and speculation on their potential impact on the market will no doubt continue, but only for a while.

As we deliberate, crystal growers harvest more and better product every day. As we rebuke producers, synthetic diamond jewelry steadily advances on the marketplace. As we go about our business as usual, synthetic diamonds begin a tiny trickle into traditional supply channels. Will you be prepared for the first synthetic diamond that crosses your desk?

Sharon Wakefield holds degrees in chemistry and chemical engineering from El Camino College and California State University at Long Beach, respectively, as well as a Graduate gemologist diploma from the Gemological Institute of America. She is an accredited member of the International Society of Appraisers. Before establishing a gemological laboratory in Boise, Idaho, she was a senior project engineer for a major space satellite manufacturer in Southern California. Her primary interest now are gemological research, writing, teaching and promoting higher professional standards in gemology and appraising. She is currently consulting with GIA on its new insurance appraisals course.