Frequently asked questions

How does GIA test coloured stones?


For each item submitted, a gemmologist uses a battery of traditional and advanced instruments to perform a variety of analytical investigations, including microscopic examinations and tests to determine an item’s gemmological identity and detect any treatments. The process is independently repeated by a second gemmologist, and may be further examined by additional gemmologists and researchers as needed.

Learn more about how GIA identifies coloured stones.

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