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October 1999

Diamonds:Gemology

Magnetic Personalities

Experimentation in diamond synthesis may soon bring the world more blue diamonds

Natural blue diamonds are among the rarest and most coveted, thanks in part to the mystery and allure of standouts such as the Hope or Eugenie Blue. Now comes word the dearth of blue diamonds may ease somewhat with the production of a synthetic counterpart.
Even synthetic blue diamonds are rare and difficult to manufacture, says Alex Grizenko of Ultimate Created Diamonds™, Golden, CO, which markets the material in the U.S. But production is under way in Russia.

The technology dates back to the 1970s, when the Soviet Union started to synthesize diamonds for industrial applications. Blue diamonds were of particular interest because of their hardness, high temperature resistance and electrical conductivity. (De Beers in England, General Electric in the U.S. and Sumitomo in Japan have also experimented with color diamond synthesis, but not for commercial purposes.)

How and How Much

Most laboratory– grown blue diamonds are Type IIb, though a very rare Type IaA blue diamond from Australia also exists (for a discussion of diamond types, see Professional Jeweler, August 1999, p. 30). The color is inherent, not induced by a separate step such as heating or irradiating.
Because the blue diamonds are harder than other colors to synthesize, they usually are small (mostly under half a carat) and range from $2,000 to $5,000 per carat wholesale.

The future promises increased production of the synthetic blues to be used in jewelry. For this reason, gemologists and sales associates should be prepared to tell the difference whenever possible. The winter 1998 issue of Gems & Gemology, the quarterly journal of the Gemological Institute of America, contains a chart showing differences between natural– color blue diamonds and synthetic counterparts. Here are some of the characteristics:

  • Magnification. In synthetic blue diamonds, metallic opaque inclusions are often visible under low magnification or even to the naked eye. These particles – from molten metal alloys in the presses in which they're grown – become trapped in the crystal during growth. Opaque metallic inclusions aren't seen in natural blue diamonds.
  • Magnetism. These metallic alloys can be magnetic if present in a faceted diamond in sufficient size.
  • Fluorescence/phosphorescence. With synthetic blue diamonds, the typical fluorescence in short– wave ultraviolet radiation is a weak to moderate blue or greenish blue. While this feature may be observed in natural– color blue diamonds also, the synthetic counterpart is more likely to phosphoresce (the color glows for some time after the short– wave ultraviolet unit is turned off.) Fluorescence also can reveal angular growth patterns and graining, which is typical of synthetic diamonds.
  • Color zoning. Short– wave radiation in synthetic blue diamonds may reveal angular graining such as cross or hour– glass patterns.

    If you examine a blue diamond and can't find any diagnostic characteristics that would indicate a synthetic, don't assume it's natural yet. In cases where determinations are elusive by conventional tests, send the stone to a qualified gemological laboratory.