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.

Hong Kong's evaluation of diamond color is that colorless to yellow is divided into 100 colors by colorimeter, so it is called "Baise Grade", which is adopted in China. Gemological Institute of the United States is colorless to yellow, and it is divided into D, E, F, …, U, V, W and other color grades, which are adopted by De Beers Company of South Africa.

At present, the evaluation of diamond color grading mostly adopts the comparison method, that is, under the standard white diamond lamp, the diamond to be graded is compared with the "standard diamond sample". 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.

For other colors beyond the grading standard, such as red, blue, purple, etc. Because it is extremely rare, diamonds of this color are all treasures in diamonds, and their prices are far higher than the pricing standards of ordinary diamonds. For example,1On April 28th, 987, at a gem auction at Christie's in London, the weight of a stone was only 0. The transaction price of 95 carats of fuchsia diamonds was as high as $880,000.

According to different colors, precious diamonds have the following varieties:

1. water purification diamond: a colorless and transparent diamond, as pure as water, especially with a light blue color. The world's super-large diamonds and world-famous diamonds are mainly of this variety, such as "Jonkel".

2. Red diamond: a transparent diamond from pink to bright red, in which "pigeon blood red" is a rare treasure. For example, Australia is the main source of the world-famous diamond "Rose Red".

3. Blue diamond: a kind of transparent diamond, which has sky blue, blue to dark blue, and dark blue is the best. This diamond is different from all other colors. It has semiconductor characteristics. Because it is extremely rare, it is a rare treasure. For example, the world-famous diamond "Hope" and so on, the Premel mine in South Africa is its main source.

4. Green diamonds: light green to green transparent diamonds, of which bright green is the best. Such as the world-famous diamond "Dresden Green". Zimbabwe (Rhodesia) is its main source.

5. Purple diamond: a kind of transparent diamond from lavender to purple, especially the bright purple one is a rare treasure, and the former Soviet Union is its main source.

6. Golden diamond: a kind of golden transparent diamond, which is a common variety in colored diamond.

7. Black diamonds: Black diamonds can't be used as diamonds, but large black transparent diamonds can also be precious diamonds, such as the world-famous diamond "Africa Star".