Look for a grading report from a reputable lab such as GIA, IGI, or HRD
Check the diamond’s clarity grade on the certificate
Use a jeweler’s loupe or microscope to inspect inclusions and blemishes
Verify the diamond with a diamond tester
Check for laser inscription on the girdle matching the certificate number
Review the 4Cs, especially clarity and color
Ask a certified gemologist to examine the stone
Compare the diamond under magnification in different lighting conditions
Confirm whether the stone is natural or lab-grown through lab documentation
Test for fluorescence if needed, since it can affect appearance but not purity