GIA is the abbreviation of American Gemological Institute, which founded and put forward the international grading system. Founded in Los Angeles 193 1, the institute has been trusted by the world in diamond classification and gem identification, and has a history of more than 70 years. The first diamond grading system in the world was formulated by GIA, and most diamond standards in the world, including China, were formulated with reference to GIA diamond grading standards. As an independent non-profit organization, it is the most authoritative diamond appraisal institution in the world at present.
GIA does have the reputation of 1 in the certificate, because its cost is the highest, generally above 300 yuan, and the prices of different national inspection certificates range from tens to 100. The difference between the two is as follows: GIA mainly focuses on cutting, the division of cutting is forbidden, and the color clarity is loose.
The national inspection requires strict color clarity, and the cutting is relatively appropriate.
The national inspection certificate is valid only in China. According to the classification regulations of national inspection, only diamonds with less than 20 marks need to be authenticated, and the diamond 4C classification certificate is not mandatory.
There is no difference between diamonds with GIA certificate and diamonds with national inspection certificate. GIA is the founder of Diamond 4C, and the GIA standard is taken as a reference by appraisal institutions all over the world, while diamonds with national inspection certificates are only valid in China. There is usually a slight difference between diamond color and diamond clarity for grading standards. GIA's testing standards tend to be diamond cutting, while (national inspection) testing standards tend to be diamond color and clarity. GIA certificate data is more detailed. However, the data of NGTC national inspection certificate is somewhat simplified.