The Gemological Institute of America (GIA) is the world's most respected independent gemological institution on diamond grading. It is the creator of the diamond clarity standard for evaluating the purity of a diamond, as well as the diamond color scale, both of which have become internationally recognized standards for grading diamond quality.

A GIA Grading Report provides facts about a diamond’s "4C" characteristics, important basic gemological identification information that every prospective buyer should possess. 

GIA administers a clarity rating based on the size, type, number, location, hue, visibility and nature of the inclusions that exist within a diamond. Diamond clarity ranges from Internally Flawless (IF) to Included (I1, I2, I3).

GIA has been grading diamond body color on a D–Z scale since 1953.