Gia is a certificate or appraisal report. It can also issue gia certificates for artificial diamonds, but it will be marked as artificial diamonds.

Subscription diamond, as the hardest mineral in nature, can naturally be tested from all sides. IGI International Gemological Institute, GIA American Gemological Institute and NGTC National Gemological and Jade Quality Supervision and Inspection Center are all authoritative institutions for testing diamond quality standards.