1, color scale: from D-Z, it can be roughly divided into five grades, in which D, E and F are the best colorless, D is the best, and E and F are the second. After that, G, H, I and J are suboptimal and close to colorless.

After that, the grades from K-Z are colored, K, L and M are yellowish, and N-Z is the worst yellowish.

2. Clarity: from F to I, it can be roughly divided into five grades .. F and IF are the best grades, almost transparent, very precious and rare. VVS 1 and VVS2 are high-grade products. Followed by SI 1 and SI2. Then I 1, I2, I3.

3. Cutting: It can be divided into six grades, namely excellent, very good, good, medium, average and poor.

Extended data:

Founder of diamond 4C standard.

American Gemological Institute. Shipley, the founder of GemologicalInstituteofAmerica Gemological Institute, founded GIA in Los Angeles on 193 1. At first, he trained jewelers how to evaluate the wholesale price through evening classes and correspondence courses.

1953, GIA established its first laboratory in new york and began to issue diamond appraisal reports. Later, GIA established two other laboratories in SantaMonica, California and downtown Los Angeles, which were officially named GemTradeLaboratory. Company, GTL is a full-time evaluation and non-evaluation subordinate to GIA.

Baidu Encyclopedia-Diamond 4c

Baidu Encyclopedia-4C Standard for Diamond Identification