Generally, the GIA color classification developed by American Gemological Institute is used to distinguish colorless series diamonds. The more transparent and colorless a diamond is, the more precious it is. The closer to z, the uneven composition, poor fire color, relatively inferior, and lower value. According to the classification of diamond color scale, we can know that the more transparent and colorless the diamond is, the more precious it is, while the closer it is to Z, the uneven composition, poor fire color and relatively inferior. D-class diamonds are completely transparent and colorless, and they are still excellent in colorless series diamonds. Diamonds will be distinguished according to the color of doping. Diamonds are almost colorless. Class F means that only a few colors can be detected. In the diamond color scale, the closer the letter is to the diamond of Z, the lower the color scale is.