Very reliable. The certificate of Guangdong Jewelry Appraisal Institute is one of the most reliable certificates in South China. Certificate inquiry can be made by telephone or online, as long as it is consistent with the data on the certificate.
The certificate inquiry and gdtc certificate of Guangdong Gold, Silver and Jewelry Testing Center are reliable. The certificate of Gdtc is reliable, and GDTC is the symbol of Guangdong Gold, Silver and Jewelry Testing Center. Guangdong Gold and Silver Jewelry Testing Center Co., Ltd. is a jewelry product quality testing station approved by China People's Bank and authorized by Guangdong Bureau of Quality and Technical Supervision.
GTC is also ok, as long as it is certified by CNAS and CMA, it is almost the same.