If the diamond is over 30 points, it is better to provide GIA certificate, which is more authoritative. For example, in Buyi Village, GIA certificates are provided for diamonds with a score of more than 30 points, and re-inspection is supported before payment. Regarding whether this is a scam, if in doubt, you'd better not buy it. After all, if this kind of thing is true, it will cost tens of millions, and if it is fake, it will probably cost a few dollars.