Diamond grading
The grades on a diamond report: clarity, color, cut and carat, and what each letter and number means.
Test yourself: Diamond grading quiz
Clarity 5 symbols
Color 2 symbols
Cut 11 symbols
Carat 1 symbol
About diamond grading
A diamond grading report describes a stone by four qualities: clarity, color, cut and carat weight. The system was developed by GIA in the 1950s and is now used across the trade. In the US, the Federal Trade Commission’s jewelry guides also limit words such as flawless, blue white and brilliant.
Clarity
Eleven grades, from Flawless to Included, judged under 10x magnification.
Color
The D-to-Z scale, from colorless to light yellow, brown or gray.
Cut and carat
The cut grade runs from Excellent to Poor for a standard round brilliant. Carat is weight: 200 milligrams to the carat.
Sources
- Diamond Quality Factors (GIA), Gemological Institute of America, The 4Cs
- Diamond Clarity (GIA 4Cs), Gemological Institute of America
- Guides for the Jewelry, Precious Metals, and Pewter Industries (16 CFR Part 23), 16 CFR Part 23 (1 January 2021 edition), Federal Trade Commission, published by the U.S. Government Publishing Office, §§ 23.13, 23.15
Researched, edited and approved by Rory Hansen before publishing. Last reviewed September 27, 2026. How we research
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