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.

An examination of the skull-melting technique used to produce cubic zirconia, first introduced in 1976, as well as the market status of this diamond simulant and information about its production and ...

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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 ...

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.

Conch "pearls" are calcareous concretions produced by the Queen conch mollusk, Strombus gigas, which is found in various areas of the Caribbean. Although conch"pearls" occur in a range of colors, the ...

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

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

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 ...

Chameleon diamonds are among the rarest of gem diamonds. This article reports on a unique collection of 39 chameleon diamonds ranging from 0.29 to 1.93 ct, which exhibited temporary changes in color ...

Gem-quality bright blue to green “Paraíba”-type Cu-bearing tourmaline is now known from deposits in Africa (Nigeria and Mozambique), in addition to three commercial localities in Brazil (in Paraíba ...

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