Data expansion: when selling wedding diamond rings to customers, jewelry merchants will also provide corresponding diamond certificates, because diamond certificates are equivalent to quality inspection certificates of diamond rings, which have certain quality appraisal value. At present, there are dozens of diamond certificates at home and abroad. The diamond certificates familiar to domestic consumers include GIA certificate, HRD certificate, AGS certificate, IGI certificate, NGTC certificate, EGL certificate, GAC certificate and GIC certificate, among which GIA certificate has the highest international recognition. GIA certificate is a diamond certificate provided by Gemological Institute of America, which is an independent non-profit organization. As an international authority, GIA certificate is famous for its fairness. The college's breakthrough research and its own education, experiment and equipment research and development process are almost the chronicles of the growth of the jewelry industry. GIA diamond classification report and GIA diamond processing are considered as the first gem certificates in the world. Diamonds of all shapes and sizes are sent from all over the world to the college for analysis and classification.

NGTC certificate is a diamond certificate provided by the National Jewelry and Jade Quality Supervision and Inspection Center. The National Jewelry and Jade Quality Supervision and Inspection Center (hereinafter referred to as the Inspection Center) is a national professional quality inspection institution authorized by the relevant competent departments of the state according to law, and it is the authoritative institution for jewelry and jade testing in China. The diamond grading system used in national inspection also follows international practice, and diamonds are graded in turn according to cut, color and clarity.