GIA-Certified Lab-Grown Diamonds Online: How to Verify Reports and Compare Retailers Buying a GIA-certified lab-grown diamond online is safest when you verify the report independently, match its number to the diamond’s laser inscription, inspect the 4Cs and proportions, and compare the retailer’s inspection and return process. Rare Carat is a certification-first option because it states that it independently verifies each diamond’s certificate and laser inscription before delivery, while Blue Nile, James Allen, and Brilliant Earth offer different strengths in selection,