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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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Rainbow hematite from Brazil’s Andrade mine.
Iridescence in Metamorphic “Rainbow” Hematite

Analyzes the substructures that cause the intense iridescence observed in “rainbow” hematite from Minas Gerais, Brazil.

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The Identification of Blue Diffusion-Treated Sapphires

Blue diffusion-treated sapphires are becoming more prevalent than ever before.

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Color zoning in amethyst from Boudi, Morocco
Amethyst from Boudi, Morocco

An introduction to Moroccan amethyst, which features distinctive color zoning and inclusions.

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Colombian Emeralds
Classifying Emerald Clarity Enhancement at the GIA Gem Trade Laboratory

One of the greatest concerns with emerald filling is the degree of clarity enhancement such treatment represents

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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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Iridescence in iris quartz from Jalgaon, India
Causes of Iridescence in Natural Quartz

Describes the occurrence of iridescence, and the role of differential etching, in quartz crystals from India’s Jalgaon District.

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Faceted blue zircons
Reversible Color Modification of Blue Zircon by Long-Wave Ultraviolet Radiation

Determines whether blue zircon, inadvertently altered to brown by exposure to long-wave UV radiation, can be restored to its original color through the use of incandescent light.

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Hydrogen-rich Diamonds
Gray-To-Blue-To-Violet Hydrogen-Rich Diamonds from the Argyle Mine, Australia

The Argyle diamond mine is the only known source of type IaB hydrogen- and nitrogen-rich diamonds colored gray to blue to violet.

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Gem-Quality Andalusite from Brazil

idely known as a rock-forming mineral, andalusite is not frequently encountered as a gem material.

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