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Paula Crevoshay’s “Yogo Columbine” sapphire pendant
The Role of Silicon in the Color of Gem Corundum

Considers the previously unreported but critical impact of silicon on the coloration of gem-quality sapphire.

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Rough CLIPPIR diamonds
The Very Deep Origin of the World’s Biggest Diamonds

Explores an exceptional family of diamonds, referred to as “CLIPPIR” (Cullinan-like, Large, Inclusion-Poor, Pure, Irregular, and Resorbed), that formed in a superdeep environment.

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Dalmatian stone samples
True Colors of “Dalmatian Jasper”

Discusses the mineralogical composition and provenance of this spotted decorative gemstone.

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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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Emerald crystals from Colombia, Afghanistan, and Zambia
Photoluminescence Spectra of Emeralds from Colombia, Afghanistan, and Zambia

Compares PL spectroscopy data of 48 emerald samples from three countries to evaluate the usefulness of the technique in geographic origin determination.

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Montana sapphires after two rounds of heating
Big Sky Country Sapphire: Visiting Montana’s Alluvial Deposits

Documents a visit to the upper Missouri River and Rock Creek sapphire mining areas.

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Two variscite cabochons from central Tajikistan
Variscite from Central Tajikistan: Preliminary Results

A look at the gemological properties and chemical composition of this light blue to light green to green gem material, which is suitable for cabochon cutting.

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Various colors of nephrite
Characterization of Mg and Fe Contents in Nephrite Using Raman Spectroscopy

Evaluates the usefulness of Raman spectroscopy in distinguishing the color varieties of nephrite based on the relative ratio of Mg to Fe concentration.

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Particolor tourmaline crystal from Luc Yen, Vietnam
An Update on Tourmaline from Luc Yen, Vietnam

Reviews the characteristics of tourmaline from pegmatites in the Luc Yen district of northern Vietnam.

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Sapphire Chart Article: Suggested Reading on Sapphires and Their Inclusions

Suggested Reading on Sapphires and their Inclusions

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