It is a common problem that the understanding of diamond certificate is not clear enough, or vague. Friends often complain that the international certificate of rough diamond clarity grade is "VVS", but in some domestic testing institutions it is "VS"; Or it is clear that the color of the international certificate is "F", but it is only "H" when it comes to national inspection. What's going on here? ! \x0d\ Information source: Diamond Express Jewellery Network \x0d\ Here, many people who have bought diamonds say that the testing standards of the national inspection are too strict, or "only the strictest, not the most accurate", because the national inspection can achieve "VVS" diamonds, which can be said to be achieved with almost no inclusions under a ten-fold magnifying glass ~ Because we use a ten-fold hand-held magnifying glass to pick diamonds, and the national inspection is doing this. Please note that this is the grading certificate of "inlaid diamonds", and the grading certificate of rough diamonds made by the state inspection is definitely not so harsh. \x0d\ Source: Diamond Express Jewelry Network \ x0d \ x0d \ Then why is the certificate of diamond setting so harsh? This is because the judgment of diamond grade will be influenced by many factors after the diamond is inlaid. \x0d\ Information source: Diamond Express Jewelry Network \x0d\ First of all, the clarity: \x0d\ It is impossible to accurately judge the clarity of inlaid diamonds. Because the clarity classification of bare diamonds is to check the crown, pavilion and waist ~, while the clarity classification of inlaid diamonds can only be observed from the crown, and some can check the waist, but due to the limitation of style, it is almost impossible to check the clarity of diamonds from the pavilion. Anyone who has been engaged in diamond classification knows that many inclusions in diamonds may not be observed from the crown, but they are very easy to see from the pavilion. \x0d\ Information source: Diamond Express Jewelry Network \x0d\ Besides, color: \x0d\ Only bare diamonds can correctly compare colors, because there are many strict requirements for diamond color grading. When grading bare diamonds, the waist edge with the richest color of diamonds must be downward, while the surface of inlaid diamonds is upward, so that the fire color of diamonds will largely cover the body color of diamonds. Therefore, moreover, after the diamond is inlaid, the color will be affected by the color of the surrounding inlaid metal. If the side is equipped with white metal, the color of the diamond will be white, and when it is surrounded by yellow metal, the color of the diamond will also be yellow. \x0d\ Source: Diamond Express Jewellery Network \x0d\ Therefore, if the metal inlaid around the diamond is white, the inspectors will consciously reduce the color of the diamond they see, so there will be deviation in color gradation judgment. But please note that when the color of the diamond itself is high, this deviation will be even greater. This is because "H" color diamonds basically have no yellow tone in the color classification of diamonds, while "D-G" high-grade diamonds do not mean that the higher the grade, the whiter the color, but that the higher the color grade, the more transparent the diamond, so the "D" color diamonds are very transparent, not very white, which must be noted, because it can be observed when comparing standard diamonds with colored stones. \x0d\ Information source: Diamond Express Jewelry Network \x0d\ Therefore, when judging the mosaic grade of this high-colored diamond, it is very easy to have a big deviation, because as I said earlier, the diamonds in this range are more transparent than those in Huang Tiao, and the human eye is far more sensitive to the depth of Huang Tiao than to the degree of transparency. At this time, the diamonds have been inlaid and are influenced by diamonds. Therefore, it is not difficult to understand that the color grade of high-color inlaid diamonds will be very different from the original bare stones. \x0d\\x0d\ There is another key point: when a diamond is set, it will definitely come into contact with metal, which means that after the diamond is set, part of it will be blocked by claws, or when the diamond is set, the outer ring of the diamond will be surrounded by metal. At this time, when checking the clarity of inlaid diamonds, these places covered by metal can't be seen at all, that is, they are being checked. Therefore, there are many blind spots in the clarity inspection of inlaid diamonds. In other words, if the clarity grade of inlaid diamonds is "VVS", perhaps the grade of loose diamonds may not be "VS". \x0d\ So the clarity level of inlaid diamonds will be very harsh. \x0d\ Source: Diamond Express Jewelry Network \x0d\ So, will diamonds with GIA's rough diamond grading certificate be downgraded when they arrive at the national inspection? \x0d\ The answer is no. If all my friends have read it carefully, I believe they will have a good idea of how to judge the level of national inspection. The reason why the national inspection and some domestic testing institutions downgrade some diamonds with international certificates is not that the inspectors of the national inspection are incompetent, because they can't judge the grade, so they will only be downgraded, or because the inspectors have no "relationship" with the testing institutions, they will downgrade diamonds with sufficient grade, hehe. When domestic testing institutions confirm that the inlaid diamond is this one on the international certificate, they will make their own grade judgment with reference to the grade on the original stone certificate. I believe that if the rough diamond grading certificate is also issued in China, the grade will definitely not be very different from GIA's rough diamond certificate, but there will be some differences if it is inlaid with diamonds. I believe that friends who have carefully read the reasons mentioned above will understand.