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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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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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A blue synthetic star sapphire from past production of Wiede’s Carbidwerk
Synthetic Star Sapphires and Rubies Produced by Wiede’s Carbidwerk, Freyung, Germany

Details the process used by Wiede’s Carbidwerk to produce star synthetic corundum from the mid-1950s through the 1970s.

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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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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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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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Update on Ammolite Production from Southern Alberta, Canada

There have been a number of changes in Ammolite production from southern Alberta, Canada, since 2001.

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Nanocut Plasmaetched Diamonds
Cutting Diffraction Gratings to Improve Dispersion (“Fire”) in Diamonds

A new microlithography process developed to create high-resolution diffraction grating patterns on portions of certain facets can improve the dispersion of light and thus the amount of “fire” in a diamond.

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Color bars on top and sides of 3,019 ct rough opal
The Challenges of Cutting a Large Gem Opal Rough

A first-person account of cutting a 3,019 ct piece of white opal to create a 1,040 ct gem with play-of-color across the surface.

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Gota de Aceite: Nomenclature for the Finest Colombian Emeralds

The finest and rarest emeralds are sometimes said to have an optical effect called gota de aceite.

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