A chemical and spectroscopic comparison of two purple gem spinel samples, one of them the first reported example of a spinel with a saturated purple color caused predominantly by chromium and cobalt.

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GIA ensures accurate gemological measurements across its global laboratories through rigorous metrology practices, including systematic instrument calibration, validation from traceable standards, and ...

Field Report Gems & Gemology, Winter 2016, Vol. 52, No. 4 Update on Gemstone Mining in Northern Mozambique Wim Vertriest and Vincent Pardieu ...

Blue diffusion-treated sapphires are becoming more prevalent than ever before. The diffusion technique, which involves the addition of color-causing chemicals during heat treatment, results in a thin ...

The sapphire deposit at Penglai, on Hainan Island, is potentially the largest in China. Gem-quality sapphires, at least one as large as 35.5 ct, have been found in alluvial gravels approximately 2 km ...

Field Report Gems & Gemology, Fall 2013, Vol. 49, No. 3 Three Occurrences of Oregon Sunstone Duncan Pay, Robert Weldon, Shane McClure, and Kevin Schumacher ...

Learn more about the GIA Diamond Origin Report service which includes a country of origin opinion for eligible diamonds.

Observing a water drop’s interaction with opal, as well as refractive index, can confirm a specimen’s hydrophane nature with less risk of breakage than total immersion.

Results from spectroscopic analyses of GE POL high-pressure high-temperature (HPHT) annealed nominally type IIa diamonds are presented, and these spectral characteristics are compared with those of ...

PDF versions of the GIA Laboratory-Grown Diamond Reports are available on Report Check. Look for an icon in the upper right hand corner. Once downloaded, the report can be printed for your records.

Several diamonds were treated for the purposes of observation and report with a new laser technique which does not show the typical surface-reaching drill hole.