See if the inspection agency is legal. The state has strict qualification requirements for jewelry and jade quality appraisal institutions, and the appraisal certificate issued is only valid if it passes the review. Cma, cal and CNA are common in the certificate of jewelry and jade appraisal.

Cma is the symbol of qualified measurement certification of testing institutions, and the institutions with this symbol are legal testing institutions;

Cal is the symbol of inspection institutions recognized by national quality inspection, and institutions with this symbol are qualified to make arbitration inspection conclusions;

Cnas is recognized by China National Accreditation Committee for Conformity Assessment, which is formed by the merger and reorganization of former China Certification Body National Accreditation Committee (cnab) and China Laboratory National Accreditation Committee (cnal), and supports international mutual recognition.

Any of the above three marks is valid, especially the first mark cma, which is the basic requirement of national laws for testing and inspection institutions.