How to Read a Gemstone Certificate

A gemstone certificate is issued by an independent laboratory and documents the stone's identity, weight, measurements, and any treatments it has undergone. Reputable labs include GIA, IGI, and GRS.

Start with the identification line — it confirms the species (e.g. 'Natural Sapphire'). Next, check the weight in carats and the measurements in millimetres, and match them against the listing.

The most important field is treatment. 'Unheated' or 'No indications of heating' commands a premium, while 'Heated' is common and accepted. Finally, verify the certificate number against the lab's online database.