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Summer 2015 G&G: Dual-Stars, Photomicrography Guide, Rubies from Tajikistan, New Micro-World Section

G&G Brief presents an overview of the content of the Summer 2015 issue of Gems & Gemology.

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Large Brazilian cat’s-eye emerald.
Large Cat’s-Eye Emerald from Brazil

A translucent Brazilian emerald exhibiting pronounced chatoyancy is examined.

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The Hidden Beauty of Amber: New Light on an Old Subject

The surprising inner world of inorganic inclusions in amber is explored through the use of polarized light and microscopic techniques.

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Some Unusual Sillimanite Cat's-Eyes

Inclusions cause chatoyancy in these rare gems.

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15 ct tanzanite
Pleochroism in Faceted Gems: An Introduction

Describes the phenomenon of pleochroism and its complex effect on the appearance of colored stones.

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Optimizing Face-Up Appearance in Colored Gemstone Faceting

How contrast patterns can increase perceived brightness and optimize a gemstone's appearance.

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Natural Mixed Cape Diamond
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Mixed-Type Cape Diamond

A natural cape diamond with unusual features is examined in the New York lab.

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0.76 ct HPHT-treated Diamond
“Fluorescence Cage”: Visual Identification of HPHT-Treated Type I Diamonds

HPHT-treated type I diamonds of various colors may exhibit unusually intense fluorescence at the facet edges and junctions.

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The Identification of Zachery-Treated Turquoise | Gems & Gemology

Millions of carats of turquoise have been enhanced by a proprietary process called the Zachery treatment.

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Hackmanite/Sodalite from Myanmar and Afghanistan

Significant amounts of gem-quality sodalite/hackmanite—some unusually transparent—have been produced.

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