GIA - Gemological Institute of America Carat Color Clarity Cut
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GIA wants you to understand exactly what you're buying when shopping for your diamond. As creators of the 4Cs and the International Diamond Grading System™, GIA set the standards for diamond grading and has been helping consumers make educated diamond buying decisions for over 50 years.

GIA's D-to-Z color-grading scale, Flawless-to-I3 clarity-grading scale, and Excellent-to-Poor cut-grading scale are recognized by gem and jewelry professionals everywhere. And, by extension, the GIA Diamond Grading Report, Diamond Dossier®, and Gemological Identification Report are considered to be the world's premier evaluations of gem quality and authenticity.