Diamond is the hardest substance in the world, and its mineral hardness is 10. When a completely transparent diamond with almost no defects is cut into a certain shape, it is called "diamond polishing". The quality of the finished diamond is determined by four conditions, namely, color (color), clarity (clarity), carat and cutting. Because the English word "C" begins, it is called "four C standard". "The whiter the better, colored diamond: the color of yellow diamonds (or slightly brown, mostly gray). According to the amount of yellow, China's national standards classify colored diamonds into 12 color grades, with diamonds with the highest color grade of D, 1O0 and 99 colors with high color grade not only rare in the market, but also expensive, so it is unnecessary for ordinary consumers to pursue such a high color grade. Usually installed in a pair of platinum diamond jewelry trust, you can use the platinum white contrast Committee, if not with yellow diamonds, you can own it. Commercial diamond jewelry, these yen, the most important color scale is probably 93-95. Of course, for special-purpose large diamond series (1 carat is more important), it is necessary to emphasize the level of color, and the higher the color, the more valuable it is.

According to the national standard, observe the cleanliness with a magnifying glass, and use VVS 1, VVS2, VS 1 and SI 1 under the conditions of VS2, Si2, level 1, level 2 and P3. In practical use, most of them are combined into five, without any defects, with flawless grade, slight defects of VVS grade, obvious defects of middle grade and tangible defects, and phosphorus grade. Except for professionals, it is difficult for ordinary consumers to find a certain kind of flaw in diamonds, not just the kind invisible to the naked eye, with a magnifying glass of 10 times. Therefore, the quality of jewelry diamonds with SI or above is completely acceptable.

The carat of a diamond is the unit. According to international rules, the weight of one carat is equal to 0.2g, and 1 carat is equal to 100 integral. Because diamonds are rare and precious with small particles, even if the weight exceeds 1 carat, they are still large diamonds. Most of the diamonds sold in this commodity are 23 to 1 dozen.

For non-professionals, it is difficult to judge the quality of diamond cutting, because if you want to cut it in detail inspection, you must use complex special equipment. Three points that can be roughly determined. 1, when the standard required for diamond cutting, the waist size (i.e. the maximum drilling diameter) and the weight of the diamond are fixed, as shown in Table 2. As can be seen from the table, this diamond weighs 25 cents and has a diameter of 4 mm. The diamond with carats on the back has a diameter of 6.5 mm.. In most cases, the diameter of commercial diamonds is always very small, for example, the diameter of a hole is 25 minutes and 3.8 mm, and the diameter of a carat diamond is 6.4 or 6.3 mm, 6.0 mm, or even. From a larger deviation, to reduce defects, the question is whether to observe the edge of the diamond waist from 0. 1- 0.2 mm, 2, which is the thinnest side. The benefits of a thin waist are mostly local thickness. 3. Observe the brightness of the diamond, that is, only diamonds with the same weight are cut well compared with the drill beam. For large-scale exercises, cut the budget, but use a detailed and published data to illustrate their advantages and disadvantages.

For diamond jewelry, such as platinum diamond ring, the diamond quality evaluation should be relatively simple, only divided into five grades, namely excellent, good, good, medium and average. Based on the grading standards, only the color and cleanliness are considered, and the cut is not considered.