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).
In China, ordinary people generally measure the value of diamonds by weight. Actually, it is not scientific. Because small diamonds are very popular in China. Therefore, the more popular concept is high-quality diamonds. High-quality and bright diamonds generally grasp the three principles of 4C: clarity, color and cut, and the three standards must reach a certain standard at the same time.
Extended data:
I. IGI International Gemological Institute-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.
Second, the special situation of diamonds.
In general, the value of diamonds can be identified by 4C parameters, except colored diamond.
Third, the important proportion.
The important proportions of diamond 4C are: weight 40%, color 20%, clarity 20% and cut 20%.
Baidu Encyclopedia-Diamond 4c
Baidu encyclopedia-diamond ring