When you get the gem and certificate, you don't need to look at the conclusion on the certificate first. You can see if there are these signs on the certificate first. Having these signs means that you have been recognized or authorized by the corresponding units.

①CMA: English abbreviation for China Metrology Certification/Accreditation.

②CAL: English abbreviation for China Laboratory.

③CNAL: abbreviation of China National Accreditation Committee for Laboratories.

④CNAS: abbreviation of China National Accreditation Committee for Conformity Assessment.

Any of the above four marks is valid, especially the first mark CMA, which is the basic requirement of national laws for testing and inspection institutions. If these four signs are not available, you are likely to get a false certificate.

2. Look at the certificate seal again.

Generally, domestic certificates must be stamped with the steel seal of the appraisal institution when they are made, but not necessarily abroad. If the jewelry photos on the certificate are printed electronically, then the steel seal does not need to be pressed; If the photo is pasted, then the steel seal must hold down the picture, as shown above.

3. find a scale to weigh it.

If you buy a bare stone without inlay, the weight of the bare stone will be indicated on the certificate; If you buy a finished product, such as a ring, the total weight of the ring will be marked on the certificate. Jewelry is generally light, and the weight on the certificate will be accurate to two decimal places, and the unit is g, so we must find an electronic scale with high precision and small error to weigh the jewelry to see if it is consistent with the label on the certificate.