I. Carat (carat)

Carats are the unit of weight of diamonds. One carat is equal to 100%(0.50 carat is equal to 50 minutes), and the weight is equal to 0.2 gram. Usually, the weight of round diamonds is about 0.30, 0.50, 1.00 carats.

Second, CLARITY.

The clarity of a diamond is usually classified by using a magnifying glass with a magnification of 10 to classify the internal and surface defects of the diamond and their influence on the luster. According to the national inspection standard of China, it is subdivided into LC, VVS 1, VVS2, VS 1, VS2, SI 1, SI2, P 1 and P2.

Diamonds are divided into five grades: excellent, very good, good and relatively good. P-class drill is also called I-class drill. Diamonds below grade P are generally not used as gems, so they are generally only classified as grade P, and are no longer classified as P 1\P2\P3.

Third, COLOR (color)

Diamonds have many natural colors, from precious colorless (white after cutting), rare light blue and pink to common light yellow. The more transparent and colorless, the more white can penetrate, and the richer the color after refraction and dispersion.

The grading of diamond color is determined by technicians repeatedly comparing the diamond to be graded with the standard color colorimetric stone in the grading environment of professional laboratories.

The whitest diamond is classified as D (starting with the first letter of the diamond). The color of diamonds is divided into 1 1 grades, which are D, E, F, G, H, I, J, K, L, M and N in turn.

Fourth, cut (cut)

Diamond cutting refers to the accuracy of its cutting and grinding ratio and the perfection after finishing. Good cutting should reflect the brightness and fire color of the diamond as much as possible, and try to keep the weight of the original stone.

The cutting grades of IGI International Gemological Institute are divided into ID (standard), EX (excellent) and VG (very good) G (good) from high to low, and the domestic national inspection is divided into VG (very good) and G (good).

Extended data:

International Gemological Institute (IGI) ——IGI Diamond Grade Certificate

IGI, the International Gemological Institute, is the world's largest independent gem identification laboratory and gem research and education institution. It has 65,438+05 laboratories and schools in major diamond trading centers and central cities around the world (Antwerp, new york, Toronto, Dubai, Tokyo, Hongkong, Tel Aviv, Los Angeles and Mumbai), and gemologists from more than 96 countries around the world receive laboratory, education and scientific research services from IGI.

Rich experience, professional advice and long-term reputation for reliability and integrity make IGI synonymous with reference standards in jewelry industry. As the largest independent laboratory in the world, IGI has developed patented technologies such as laser lettering and darkroom photos, which have been appraised for decades, and initiated and popularized the 3EX cutting evaluation system. For a long time, it has been a global leader and norm-setter in the field of gemology.

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