2, and the milk is creamy and foggy, which seriously affects the fire color. Coffee and milk need to be seen in kind, which can be distinguished by the naked eye, and there is no indication on the certificate.
Extended data
The problem of GIA certificate
1. Cutting problem: GIA mechanism detects bare stones. When testing, it is necessary to rotate the diamond 360 degrees with extremely precise instruments, draw a model of the true proportion of the diamond, and calculate the "table width ratio" and "pavilion depth ratio" of the diamond by computer.
2. For each diamond tested by 2.GIA, a diamond scale map will be drawn in the certificate, which makes it easy to see the cut grade of the diamond.
3. Most of the national inspection certificates on the market are inlaid diamonds, so it is difficult to accurately measure each part of the diamond, so it is difficult to make an accurate judgment on the cutting of the diamond.
4. Color problem: There are many strict requirements for diamond color grading, and only bare stones can correctly compare colors.
5. When grading bare stones, it is necessary to compare the diamond table with the most obvious waist edge of the diamond, and the inlaid diamond table is upward, so that the fire color of the diamond itself will largely cover the color of the diamond.
6. The color of inlaid diamonds will be influenced by the color of surrounding metals. If the metal inlaid with diamonds is white, the color of diamonds will be white; if yellow metal is used, the color of diamonds will be yellow.
7. Clarity: It is impossible to judge the clarity of the diamond after setting, because the clarity of the bare stone should be checked at the crown, pavilion, waist and other parts.
8. The clarity of inlaid diamonds can only be observed from the "crown" of diamonds, and some can check the "waist", but due to the limitation of styles, it is almost impossible to check the clarity of diamonds from the "pavilion".
9. Due to the influence of the fire color of the diamond itself, many inclusions in the diamond can't be seen from the table.
10. Weight problem: GIA needs to weigh the diamonds in the sealing instrument to five decimal places when checking the weight of bare stones.
1 1. When testing the weight, it is impossible to take out the diamond and weigh it. Therefore, in China, when the diamond ring certificate is issued, the weight of the diamond printed on the inner wall of the ring by the jewelry manufacturer will be "reference nominal", "imprint nominal" and "supporting stone weight".
References:
Baidu encyclopedia -GIA certificate
Baidu encyclopedia-diamond