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.
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.
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.
True Colors of “Dalmatian Jasper”
Discusses the mineralogical composition and provenance of this spotted decorative gemstone.
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.
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.
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.
Big Sky Country Sapphire: Visiting Montana’s Alluvial Deposits
Documents a visit to the upper Missouri River and Rock Creek sapphire mining areas.
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.
A Synthetic Diamond Overgrowth on a Natural Diamond
Analysis of a diamond graded Fancy blue revealed a CVD synthetic overgrowth on natural diamond.