Generally speaking, there is no single drill inspection. If there is a HGTC certificate, that is, the national inspection certificate is not as authoritative as the gia certificate issued by the Gemological Institute of the United States, then a single diamond has not been inspected. If the inspection should be at 100 yuan ~200 yuan, you can find a jewelry store yourself and ask it to take a look for you. Weigh carat, look at the waist size, look at the location of the defect. You don't need to find an institution to identify it with a thermal conductivity meter.