Different testing institutions will inevitably have different results, but you can negotiate with the merchant before buying, and whether you can return it if it is inconsistent with the testing certificate provided by the merchant. There is also our popular certificate, which should actually be called the test report. It only provides the organization with the testing standard of this diamond, and cannot be used as an absolute legal basis. If he sells fake goods and refuses to accept the certificate, the nature will be completely different. GIA is the most authoritative international certificate, because they put forward the 4C testing standard, and testing centers all over the world use this example to customize their own standards. In China, NGTC should be better. Sure, where is the local protection? In order to show its authority, the testing center can appropriately raise or relax the standards when necessary. As long as there is not much difference, there is no way. Protect the place. Haha ~ at least domestic jewelry testing is not nonsense, and the level gap is not too much. What do you think we detected ourselves? You can't just kill them all and tell everyone that we are the most authoritative ~ people all over the world laugh ~ If there is something wrong with the diamonds you bought yourself, you can discuss with the merchants how to deal with them. Returning it means that the merchant is NB~, but the possibility is relatively small. After all, you don't have any relevant agreement before the sale, so the possibility of change should be higher. ~ I don't think the average seller of loose diamonds will offend a group of customers for a product ~ You are very satisfied with his friends.