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Spinel
The Black Prince's Ruby. The Timur Ruby. For centuries, spinel, the great imposter, masqueraded as ruby in Europe's crown jewels.
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Research
Suspended Pargasite Crystal in Pink Spinel
A euhedral prismatic pargasite crystal is identified in pink spinel.
Fissure with Moiré Pattern in Spinel
A precipitation of an unidentified mineral creates a complex moiré pattern in a fissure of a purple spinel.
Color Modification of Spinel by Nickel Diffusion: A New Treatment
Reports on a newly discovered treatment process for producing a deep blue color in natural spinel and proposes identification criteria.
Color Modification of Spinel by Nickel (Ni) Diffusion: A New Treatment in the Gem Market
GIA researchers report on a new nickel-diffusion treatment used to modify color in spinel and present criteria for identification.
Color Mechanism and Spectroscopic Thermal Variation of Pink Spinel Reportedly from Kuh-i-Lal, Tajikistan
A detailed spectroscopic investigation of the color of pink spinel reportedly from the Kuh-i-Lal deposit in the Pamir Mountains of Tajikistan.
Purple Gem Spinel from Vietnam and Afghanistan: Comparison of Trace Element Chemistry, Cause of Color, and Inclusions
Figure 1. The vivid colors seen in fine gem-quality spinel are derived from the mixing between multiple different chromophores in a range of ratios and concentrations, as in this fine 13.52 ct violetish purple spinel. Courtesy of the Dr. Edward J. Gübelin Collection. Photo by Robert Weldon/GIA.
Micro-Features of Spinel
Provides a visual guide to the internal features of natural, synthetic, and treated spinel, as well as inclusions of spinel in other gemstones.
Field Gemology: Building a Research Collection and Understanding the Development of Gem Deposits
With more than 90 field expeditions on six continents since 2008, GIA has accumulated over 22,000 colored stone reference samples. This extensive collection of colored stones with known origins supports GIA’s research on geographic origin determination.
Gemstones in the Era of the Taj Mahal and the Mughals
A look at the gem ornamentation of this landmark, as well as the jewels of the Mughal dynasty.
Quarterly Crystal: Wurtzite Phantom in Quartz
For the first time, wurtzite is found as an inclusion in gem material.
