Grade d: completely colorless. The highest color level is extremely rare.
Class e: colorless. Only a gemologist can detect a trace of color, which is a very rare diamond.
Class f: colorless. A small amount of color can only be detected by jewelry experts, but it is still considered colorless and belongs to high-quality diamonds.
G-H grade: almost colorless. Compared with diamonds of higher color grade, there is slight color difference, but diamonds of this color grade still have higher value.
I-J grade: almost colorless. It can detect slight color and has high application value.
K-M grade: dark color, poor fire color.
N-Z grade: dark color, poor fire color.
Extended data:
Different countries and regions adopt different color grading systems, but these grading systems are similar to each other. According to the colorless diamond grading system of international institutions such as IGI International Gemological Institute, the color of diamonds is divided into 23 grades, which are represented by English letters D-Z respectively. The most commonly used one is 1 1 level d-n.
The main colors of diamonds are colorless, white and light yellow. Yellow is a taboo for diamonds, and its fading directly affects the quality and value of diamonds. Therefore, the color of diamond is the primary factor in its economic evaluation. The classification of diamond color is very strict in the international jewelry industry, and all countries have their own corresponding evaluation standards.
Comparison method is often used to evaluate the color grading of diamonds, that is, the diamonds to be graded are compared with "standard diamond samples" under the standard white diamond lamp. Since this classification is based on the scheme of American Gemological Institute, it is best for the standard diamonds used for comparison to be appraised by American Gemological Institute with certificates attached.
Baidu encyclopedia-colored diamonds