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These two opals were represented as natural-color blue and pink opal from Mexico.

Update on Dyed Hydrophane Opal

Edward Boehm and Nathan Renfro, January 26, 2018

Opal purportedly from a new deposit is found to be dyed.

Article

Summer 2016 G&G: Diamonds from Diavik, Responsible Sourcing and Fabergé Cossack Figures

Jennifer-Lynn Archuleta, August 3, 2016

A summary of the content found in the Summer 2016 issue of Gems & Gemology.

Opal slices before and after water immersion

Hydrophane Opal Treatment

Ratima Suthiyuth and Vararut Weeramonkhonlert, April 28, 2016

An opal rough is immersed in water and treated with oil and Opticon to observe effects on transparency and play-of-colour.

Coated Fire Opal in the Chinese Market

Wen Han, Taijin Lu, Hua Chen, and Jian Zhang, October 31, 2014

An investigation of a coated fire opal recently found in the Chinese market.

UV-Reactive Opal

Troy Ardon, April 30, 2014

The first documented UV-reactive chemical treatment to make opal appear tenebrescent.

Water Immersion Reveals Dye in Fire Opal

Larry Tai-An Lai, October 17, 2013

A simple test easily detected dye treatment in fire opal.

A Useful Technique to Confirm the Hydrophane Nature of Opal

Nathan Renfro, October 17, 2013

Observing a water drop’s interaction with opal, as well as refractive index, can confirm a specimen’s hydrophane nature with less risk of breakage than total immersion.

Treated Andamooka Matrix Opal

Grahame Brown, June 1, 1991

Matrix opal from Andamooka, in South Australia, is a precious opal-included porous rock that is commonly colour enhanced (carbon impregnated) to imitate the highly prized black opal from Lightning Ridge in northern New South Wales, Australia.

Abstract Header from the 2009 issue of Gems & Gemology

Abstracts; Summer 2009

Brendan M. Laurs, Thomas W. Overton

This article, from the Summer 2009 issue of Gems & Gemmology, is a compilation of abstracts of important gemmology-related articles published outside of Gems & Gemmology.

Abstracts; Winter 1991

Dona M. Dirlam

This article, from the Winter 1991 issue of Gems & Gemmology, is a compilation of abstracts of important gemmology-related articles published outside of Gems & Gemmology.