GIA releases Gems & Gemology Winter 2009 issue

The Gems & Gemology (G&G) Winter 2009 issue by Gemological Institute of America (GIA), released on January 15, 2010, has a content list examining transformation and distribution of corundum sources over the last quarter century, use of nanotechnology to improve fire in diamonds, an African source of chrysoprase and prase opal, and demantoid from Italy.

Russ Shor and Robert Weldon have written the lead article “Ruby and Sapphire Production and Distribution: A Quarter Century of Change,” speaking on localities, treatments and global developments that have expanded supply and reshaped consumer attitudes regarding the gemstones. “With a wealth of sources and a variety of treatment processes that dramatically enhance low-grade material, ruby and sapphire are the world’s top-selling colored gemstones,” says Alice Keller, editor-in-chief of G&G. “This must-read article provides a solid review of today’s corundum marketplace.”

An article “Cutting Diffraction Gratings to Improve Dispersion (‘Fire’) in Diamonds”, by Al Gilbertson et al, speaks of the nanotechnology process, developed by researchers at the California Institute of Technology (Caltech), diffraction gratings being applied to selected areas on a diamond’s surface to enhance the appearance of fire.

Dr. James Shigley and coauthors have summed up articles on chrysoprase and green prase opal from central Tanzania, and Dr. Ilaria Adamo et al. updating on demantoid from Val Malenco, Italy.

The issue contains a Lab Notes section on a new chalcedony treatment, a Fancy Intense blue type IIb synthetic diamond, and turquoise with inclusions of a uranium mineral. The Gem News International section features the latest on rubies and copper-bearing tourmaline from Mozambique, dyed sillimanite as an emerald imitation, and discovery of pink-to-red tourmaline in Nigeria.