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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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Accurate Reporting of Key Trace Elements in Ruby and Sapphire Using Matrix-Matched Standards

Presents a group of corundum standards developed by GIA to improve the accuracy and efficiency of its laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) instruments.

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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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Opal from the Shewa Province, Ethiopia

Opal occurs as nodules in volcanic rocks at a new gem opal locality in the Menz Gishe district of Shewa Province, Ethiopia.

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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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CVD overgrowth on natural diamond
A Synthetic Diamond Overgrowth on a Natural Diamond

Analysis of a diamond graded Fancy blue revealed a CVD synthetic overgrowth on natural diamond.

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