I don't know about the store you mentioned, but there is generally no big problem with big stores like jewelry, and small stores can't guarantee it. But the key question still depends on you. You can ask him to issue a certificate from a regular testing company before buying. This is the most responsible way for yourself. Generally speaking, the formal certificate is the certificate of national inspection, and other institutions, such as China Uygur and China Inspection, are completely untrustworthy. You can see whether the certification authority issued by him is credible and how good it is, and then decide whether to buy it or not.