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Gemstones of the World
Books: Gemstones of the World

Review of Walter Schumann's Gemstones of the World.

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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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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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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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8.5 ct Aquamarine Cabochon
Aquamarine from the Masino-Bregaglia Massif, Central Alps, Italy

Aquamarine from granitic pegmatites of the Masino-Bregaglia Massif, Central Alps, Italy.

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chrysoberyl samples
Chrysoberyl from the New England Placer Deposits, New South Wales, Australia

Examines a collection of chrysoberyl samples from these sapphire placer deposits to determine their distinct mineralogical and chemical properties.

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Natural Mixed Cape Diamond
Mixed-Type Cape Diamond

A Fancy orangy yellow “cape” diamond featured an unexpected 480 nm band, a defect normally associated with orange color.

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Assortment of Linde synthetic star rubies and sapphires
Dual-Color Double Stars in Ruby, Sapphire, and Quartz: Cause and Historical Account

Examines a form of asterism comprising two six-rayed stars, one white and one that exhibits the stone’s bodycolor. Firsthand accounts and a survey of patent documents reveal that diffusion has been used to create or enhance this optical phenomenon in synthetic and possibly natural corundum since the 1950s.

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