Thai police and Bloomberg report that over 30,000 diamonds worth about 1.9 billion baht were smuggled into Vietnam over two years, with GIA laser inscriptions erased and re-engraved and inflated grading certificates issued. Dozens of Vietnamese jewellery shops have temporarily closed, PNJ's market value nearly halved, and some customers are selling stones back. For a Thai jeweller or gold shop, the lesson is simple: verify certificates and stone origin before buying or reselling diamonds, and be ready for buyers to ask more questions about value. The article does not report any direct effect on Thailand.