Professional Jeweler Archive: Gemesis Gemological Markers

February 2004


Gemesis Gemological Markers

Jewelers should become familiar with some potentially identifying features of Gemesis synthetic diamonds

‘We want to earn your respect,” Carter Clarke, president of synthetic diamond maker Gemesis, told an attentive crowd of diamantaires and retailers at the Rapaport Diamond Conference in New York City this past fall. “We do not want Gemesis-created diamonds to be misrepresented.” His statement met with the gathering’s complete – though guarded – approval.

Dealers and retailers have long sold diamonds on the basis of their natural pedigree. They worry laboratory-grown diamonds such as Gemesis – which share chemical, optical and physical characteristics with natural diamonds – could upset the market and jeopardize consumer confidence in natural diamonds. But they also realize synthetic diamonds such as Gemesis’ are an inevitable part of the marketplace.

Though Gemesis is working on various forms of disclosure (see “Gemesis: The Retail Marketing Plan,” p. 23), it’s still wise for jeweler/gemologists to learn some telltale characteristics of these stones.

For more than a decade, gemological laboratories around the world have maintained that synthetic diamonds produced by equipment called split-sphere BARS presses can be identified readily, particularly if these stones exhibit visual characteristics such as inclusions. This is the method Gemesis uses, though similar inclusions and observations can be drawn from synthetic diamonds manufactured by other companies too.

Using the Gemesis-created diamonds sent to Professional Jeweler, we conducted a gemological review. The photos on this page and pages 32-33 illustrate characteristics observable in most Gemesis-created diamonds to help identify them gemologically. These include: color, inclusion analysis, fluorescence patterns and color zoning.

For more information, read the Gemological Institute of America’s Gems & Gemology, Winter 2002.

– by Robert Weldon, G.G.

Photos by Robert Weldon

Fancy intense and fancy vivid diamonds should always be checked carefully if they’re not accompanied by a gemological report such as this one from the International Gemological Institute. The 0.41-ct diamond at the bottom is accompanied by the report.
Girdle Inscription
(45x Magnification)

If the stone lacks accompanying documents or visible girdle inscriptions, further testing is recommended. A microscope is the instrument of choice for jewelers and gemologists. A series of microscopic observations can help determine whether a stone you’re examining is synthetic, suspicious or natural. If assembled observations don’t lead you to a firm conclusion, further testing by a qualified laboratory is necessary.

X- Shaped
Inclusion Clouds
(10x Magnification)

Clouds of pinpoint inclusions form a loose X. Not all Gemesis stones exhibit this characteristic, though it was seen in two of five stones Professional Jeweler examined. The Winter 2002 Gems & Gemology, the Gemological Institute of America’s journal, found these pinpoint inclusions differ in appearance from pinpoint arrangements in natural Type Ib yellow diamonds. If you see dispersed clouds of pinpoints, the stone is suspicious.

X-Shaped Luminescence Pattern
(25x Magnification)

The same stone that contained the X-shaped cloud of pinpoint inclusions was observed under a long-wave ultraviolet lamp. The X-shaped luminescence pattern was clearly visible. This test should be conducted in a darkened room. Not all Gemesis’ stones (or stones from other manufacturers) exhibit this pattern. But if you see it, it’s considered diagnostic of a laboratory-grown diamond.

Color Zoning
(25x magnification)

Angular bands of colorless diamond against larger patches of vibrant diamond color are not the kind of zoning seen in natural diamonds. Distinct color zoning is visible in all Gemesis stones we examined, as are strong graining patterns. You must view the stone under magnification and under numerous viewing angles. Darkfield illumination helps find colorless zoning.

Metallic Inclusions
(60x Magnification)

Metallic inclusions such as this along the girdle edge are diagnostic of lab-grown diamonds. This was the only such inclusion observed in the diamonds we examined. Gemesis officials say they’re working hard to improve the quality of the crystals they manufacture so this kind of clue will be rare.

Copyright © 2004 by Bond Communications