Professional Jeweler Archive: Gems of a Feather

May 2001

Gems & Pearls/News

Gems of a Feather

Two bicolor rarities make the scene in the desert

The Tucson gem and mineral shows often yield unusual surprises. This year it was a bi-surprise: a bicolor topaz from Brazil and a bicolor spessartite from Africa – different species of gem with the same genre of distinction.

In addition, there’s been a new find of spessartite garnet in southern Tanzania just as interest in the gem grows.

For more information on what was popular and what was rare at the Tucson gem and mineral shows, see “Cautious Color,” Professional Jeweler, April 2001, pp. 35-37.

Story and photos by Robert Weldon, G.G.

Bicolor Spessartite

Nigeria has made news three years in a row with spectacular bicolor and rubellite tourmalines. Now bicolor spessartite has been discovered. Precious Gemstones Co., Zumbrota, MN, showed a 3.79-ct. sample in Tucson. Cutter John Dyer acquired the rough last year, and sources at the Gemological Institute of America say they’ve received at least one more sample.

Spessartite, which owes its yellow-to-orange color to manganese, was first discovered in the Spessart region of Bavarian Germany. Since then, it’s been found in many places: Brazil, Sri Lanka, Russia, China, Myanmar, Madagascar and, according to Gems: Their Sources Descriptions and Identification by R. Webster, during excavation on 179th Street in Manhattan.

Despite the number of localities, fine spessartites are considered rare. But because of recent finds in Africa and Brazil, and because of their brilliance and dispersion, spessartites are gaining popularity among gem collectors and jewelry designers.

3.79-ct. bicolor spessartite garnet from Nigeria is courtesy of Precious Gemstones Co., Zumbrota, MN; (507) 732-4262.

Bicolor Topaz

Shades of the Earth, Phoenix, AZ, showed this 11.2-ct. bicolor topaz during the Tucson gem and mineral shows.

Wayne Thomson, the company’s owner, speculates it may have been unearthed in the mid-1970s when a fluke pocket of bicolor topaz was found in Ouro Preto, Brazil.

Rare gem collectors immediately snatched up the bicolor crystals available from that find, he says, and collectors have bickered over the handful of samples that have since made it to market.

Causes of this rarity in which two colors are present (pink and orange) remain the source of some speculation. Both colors in topaz are caused by chromium.

11.20-ct. bicolor topaz from Brazil is courtesy of Shades of the Earth, Phoenix, AZ; (602) 861-1830.
New Find of Spessartite Garnets

A new find of spessartite garnet in southern Tanzania, Africa, is among a few new sources spurring interest in this family of garnets.

These rare matched pair of Tanzanian garnets – 6.55 carats and 6.54 carats –are courtesy of Gordon Bleck and Blue Fire Co., Ratnapura, Sri Lanka.

Copyright © 2001 by Bond Communications