What is the American Gem Society (AGS)?
By Jared James · Last updated 21 May 2026
Definition
The American Gem Society, usually shortened to AGS, is a professional organisation founded in the United States in 1934 to set ethical standards and educate the jewellery trade. It was started by a group of independent jewellers along with the founder of the Gemological Institute of America. AGS became best known for its diamond grading laboratory, which used a strict 0 to 10 scale and was particularly respected for how precisely it graded a diamond's cut; that laboratory has since become part of GIA.
Frequently asked questions
- What does an AGS grade mean?
- AGS graded diamonds on a 0 to 10 scale where 0 is the highest quality, the reverse of how some other labs work. It was especially known for its detailed, science-based grading of a diamond's cut.
- Is AGS the same as GIA?
- No, they began as separate organisations, though they are historically linked because GIA's founder helped start AGS. In 2022 the AGS laboratory's grading work moved across to GIA, so newer diamonds are graded by GIA.
- Is an AGS-certified diamond worth more?
- An independent grade gives you confidence in what you are buying, which supports a diamond's value, but the certificate itself does not add value. The grade simply describes the quality the diamond already has.
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