International certificates have different authorities according to their categories: for example, GIA (Gemological Society of America) and HRD (Diamond Senior Conference Alliance) are generally recognized for diamonds, and GRS (Swiss GRS Gemological Appraisal Institute) is more common in colored gems.

There are more authoritative NGTC (National Jewelry and Jade Quality Supervision and Inspection Center) and Gem Appraisal Center of Peking University. There are countless small appraisal stations: Dida, Shenzhen State Inspection and Federation of Industry and Commerce. ................................................................................................................

You don't really need to look at authority or size now. The state has a very strong control over this. No matter how big or small the appraisal station is, it is afraid to issue certificates indiscriminately. If there is a problem, the appraisal station will pay a very serious price, so as long as there is an appraisal certificate from a formal institution, it can be believed.