The national customs certificate is reliable. These certificates are issued by authoritative jewelry testing institutions and are subject to national supervision and laws. There will be some marks on the certificate, such as CNAS, ilac-MRA, CMA, CAL, CNAL, indicating that the appraisal institution is effective.

There will also be a photo of the test sample on the certificate, which can compare whether the physical object is similar to the photo. In addition, the certificate should be signed by more than two appraisers. Generally speaking, the national customs appraisal certificate is reliable.