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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A gemological investigation into natural moldavite and its more recent imitations.

ABSTRACT Aquamarine and heliodor are colored by Fe ions, an important coloring agent for beryl. Blue to yellow gem beryl was studied by quantitative spectroscopy and trace-element analytical ...

While more people are becoming familiar with lab-grown diamonds, many still don’t know how they are actually made. Learn about the two diamond growth processes, HPHT and CVD.

Lightning Ridge is the world capital of fine black opals, the most desired of all opals. In June 2015 a group of GIA field gemologists visited this legendary town in New South Wales, Australia. Come ...

Learn more about what causes a diamond to chip, and 8 tips on how you can avoid chipping your diamond.

Sri Lanka’s gemstone and jewelry industry blends traditional practices and experience with the needs of the modern global market. Photo by Andrew Lucas/GIA. To visit Sri Lanka is to experience one of ...

A behind-the-scenes exploration of the Smithsonian's Janet Annenberg Hooker Hall of Geology, Gems, and Minerals.

Diamonds have a long history as a premier gemstone—a natural consequence of their beauty, rarity, and superlative physical properties such as extreme hardness. Diamonds that are mined for use as ...

You’ve heard about the 4Cs of diamond quality (color, clarity, cut, carat weight). But how did they become so well-known? Here’s a little diamond history.

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