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.

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

Using a multi-step process, Lucent Diamonds has developed a new treatment process for certain natural diamonds that creates colors from pink-purple through red to orangy brown.

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 ...

アクアマリンは3月の誕生石であるだけでなく、 19回目の結婚記念日 のプレゼントとしても使用されます。有名なものとしては、1936年にブラジル政府が米国大統領夫人であるEleanor Rooseveltに長方形ステップカットが施されたダークブルーのアクアマリン（重量1,298ct）を贈りました。これは、2.9 ...

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 ...

Since late 2007, rubies and sapphires have been mined by hand methods from both eluvial and primary deposits at Winza in central Tanzania.

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.

専門分野で次の段階に進もうとする方も、新しいキャリアを目指す方も、GIA のコースやディプロマプログラムを受講して成功への準備をすることができます。 GIA は、独自の画期的な研究から開発され、業界をリードする ...