Summer G&G Offers New Information on Wittelsbach-Graff and Hope Diamonds, Play-of-Color Opal from Ethiopia

CARLSBAD, Calif. – Aug. 12, 2010 – The Summer 2010 issue of the Gemological Institute of America’s (GIA) Gems & Gemology, now available, features a comparison of two of the world’s most important blue diamonds, new sources of opal and cutting-edge technology for pearl identification.

In the lead article, Dr. Eloïse Gaillou and colleagues describe how they tested the famed Wittelsbach-Graff and Hope diamonds to determine if they came from the same piece of rough.

“Because these diamonds have similar color and long-lasting phosphorescence – and both are believed to have been purchased in India during the 17th century – there has been widespread speculation that they were cut from the same crystal,” says Alice Keller, editor-in-chief of G&G. “In this article, observations with the DiamondView and other tests demonstrate that the Hope and the Wittelsbach-Graff do not share a common parent.”

Next, Dr. Benjamin Rondeau and coauthors describe attractive play-of-color opal from Wegel Tena, in Ethiopia’s Wollo Province. Discovered in 2008, the deposit has produced mainly white opal, with some brown, fire and colorless opal. Most of the opal appears to be resistant to crazing.

Also in this issue, Gagan Choudhary investigates a new type of composite turquoise, while Dr. Martina Simoni and colleagues report on a new source of fire opal in Madagascar. Two articles explore X-ray computed microtomography in pearl identification: the first (by Stefanos Karampelas et al.) compares it to traditional X-radiography, and the second (by Michael Krzemnicki et al.) describes its use in separating natural from cultured pearls. Last, Thomas Hainschwang and colleagues characterize a new orangy brown gem mineral, hibonite.

Highlights from the Lab Notes section include a Fancy Vivid blue HPHT-treated diamond, a near-colorless CVD-grown synthetic diamond larger than one carat and a green beryllium-diffused sapphire. The Gem News International section features recent finds of kunzite in southern California’s Pala district, a composite coral bangle from China and a lead-glass-filled ruby discovered in antique jewelry.

G&G’s special “Retrospective of the 2000s,” an in-depth look at the localities, treatments, technologies and business developments that shaped gemology over the past decade, will be the focus of the Fall 2010 issue.

To obtain a copy of the Summer 2010 G&G or to subscribe, visit the GIA Store or contact Circulation Coordinator Martha Rivera at martha.rivera@gia.edu or call toll-free (800) 421-7250, ext. 7142. From outside the U.S. and Canada, call (760) 603-4000, ext. 7142. To purchase PDF versions of specific articles or sections, visit Gems & Gemology Online.