When consumers buy diamonds, the certificate attached to the diamonds is also very important. There are many kinds of certificates, which need to be carefully observed when purchasing. For example, the General IGI International Gemological Institute Diamond Certificate and GIA American Gemological Institute Diamond Grade Certificate are widely recognized and used internationally. The world's first complete and comprehensive diamond cutting grade map was made by IGI, which is more authoritative than other institutions in evaluating the color clarity of diamonds. In addition, there are HRD certificates, which are rare now. China also has some NGTC national inspection certificates and GIC certificates.