The methods are as follows:

1. Institutional qualification

There are four kinds of institutional qualification certification: CAL certification, CMA certification, CNAS certification and ILAC-MRA certification. CMA is the compulsory certification of appraisal institutions by the state, and it must be available. Others are voluntary, but generally large testing institutions will have these signs at the same time.

2. Contact information

On the reverse side of the certificate, in addition to the qualifications possessed by the institution, there must also be information such as the name, contact number, address and website address of the appraisal institution.

3. Inspection signature

The certificate needs to have the name of the inspector and the name of the rechecker (approver), and neither signature can be missing.

4. Identification content

Different certificates have different emphases, but the more detailed the test content, the better. The jewelry you choose should be consistent with the sample described in the certificate. Diamond grading certificate, with 4C grade; The purity inspection certificate of precious metal jewelry should have the type and content of precious metal; Jewelry and jade appraisal certificate must have accurate inspection conclusions.

5. National standard number

Jewelry testing in China follows national standards. GB/T

16552 name of jewelry and jade; GB/T 16553 jewelry and jade identification; GB/T 16554 diamond classification; GB/T

1843 nondestructive testing method for precious metal jewelry content: x-ray fluorescence spectrometry; GB

11887 regulation and naming method of precious metal purity of jewelry. Those without T are mandatory standards, and those with T are recommended standards.

6. Appraisal Seal

Every independent appraisal institution has the official seal of the department, and the appraisal certificate must be stamped with the official seal of the unit, and the content of the steel seal is used as the mark of the authenticity of the inspection certificate. The full name of the issuing agency must be printed on the steel seal, and individual agencies will also have department codes.

7. Other information

Each appraisal certificate has an independent and non-repetitive number, which is the certificate number of the certificate. Various institutions have also taken many anti-counterfeiting measures for their own rights and interests, such as NGTC anti-counterfeiting code, laser anti-counterfeiting label, logo fluorescence under ultraviolet light and so on.