Smoke on the Water: Treated Ethiopian Hydrophane Opal

Posted on March 1, 2012 by Cigdem Lule, PhD, FGA, GG (GIA)

Opal is an intriguing gemstone since mineralogically it is considered to be a common silica gel. However, in certain locations, it occurs in its precious form displaying play-of-color due to more regular internal structure compared…

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