Professional Jeweler Archive: Liddi-Coat of Many Colors

July 2000

Gemstones & Pearls/News

Liddi-Coat of Many Colors

Increasing supplies of the rare Madagascar gem named for GIA's Richard T. Liddicoat are reaching the market

Liddicoatite – a dramatic gem with a special name – is seen with increasing frequency. Found almost exclusively in Madagascar, this variety of tourmaline is marked by color banding and a three-rayed star resembling the Mercedes auto logo.

The gem, long sought by collectors, is named in honor of Richard T. Liddicoat, chairman of the Gemological Institute of America. It’s usually cut in slices to show off its unusual formation and banding. But as Madagascar reveals more and more of its gem wealth, more liddicoatite is making its way into the market, and some is faceted. Faceting erases the Mercedes logo effect, but retains the striped elegance.

Tom Cushman of Allerton Cushman, Sun Valley, ID, recently exhibited several faceted liddicoatites. “When all you’ve seen is liddicoatite cut in slices, you hardly expect to see them this way,” says Cushman, who regularly travels to Madagascar.

What Is Liddicoatite?

Liddicoatite is particolored, meaning more than three colors are visible. It differs from other particolored tourmalines because it has calcium and lithium, which produce violet and red, colors not seen in other tourmaline, says Dr. Emmanuel Fritsch at the University of Nantes in Nantes, France.

Liddicoatite may be colored also by manganese, chromium and titanium. The arrangement of the elements creates the symmetrical banding and, in the crystal, the triangular pattern.

In 1990, a faceted, purplish red liddicoatite from Minas Gerais, Brazil, was presented to Liddicoat, marking the discovery of a new source. However, Madagascar remains the classic source.

– by Robert Weldon, G.G.

Traditionally, liddicoatite tourmaline crystals are cut in slices to show the color banding (left, courtesy of Allerton Cushman & Co., Sun Valley, ID) and the Mercedes-logo effect below, gem courtesy of Overland Gems, Los Angeles, CA).
Richard Liddicoat

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