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Fancy Dark brown to Fancy black Marange diamonds
Black Diamonds from Marange (Zimbabwe): A Result of Natural Irradiation and Graphite Inclusions

Characterizes a suite of 40 natural brown to black diamonds from this deposit so that they can be distinguished from suspected treated black diamonds.

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Fluorescence Produced by Optical Defects in Diamond: Measurement, Characterization, and Challenges

How variations in UV lamp output can affect observed fluorescence color and intensity.

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Article
Pyrope Garnet and Montana Sapphires Highlight Winter 2015 G&G

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

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Optical Defects in Diamond: A Quick Reference Chart

A simple chart on optical defects in diamond, including those that produce coloration and fluorescence colors.

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Multi-colored gems are superimposed on an image of glacier peaks.
Article
Gems and Minerals from the Subarctic

Circumnavigate the boreal reaches of the globe to explore gems from polar regions.

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Three pieces of labradorite with yellow, blue and green flashes of color.
Article
Optical Effects of Phenomenal Cabochons

Learn how the structure, inclusions and properties of some gemstones interact with light to create unusual visual effects.

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A wide range of jewelry pieces with the round brilliant diamond cut
A Foundation for Grading the Overall Cut Quality of Round Brilliant Cut Diamonds

The GIA diamond cut grading system described here includes the components of brightness, fire, scintillation, polish, and symmetry, as well as weight and durability concerns, into a single overall grade for cut quality for standard round brilliants.

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Article
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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Article
Spring 2015 G&G Examines Blue Spinel, Chinese Jewelry Design and the Latest in Synthetics

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

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Whitish Graining with an Amorphous Appearance
The Impact of Internal Whitish And Reflective Graining on the Clarity Grading of D-To-Z Color Diamonds at the GIA Laboratory

This article reviews the GIA Laboratory’s history of reporting on certain types of graining which are often the only characteristics present in large, high-clarity, high-color diamonds.

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