DIAMOND CLARITY All but the rarest diamonds have small flaws, air bubbles, scratches, or other minerals. The fewer the flaws, the more valuable and beautiful the stone. Diamonds graded VVS2 to IF are rare and expensive. Most couples opt for ratings between SI2 and VS1. Cut is nearly impossible for a layperson to evaluate, so it's important to get an EGL or GIA certificate verifying diamond quality. This chart shows the clarity grading scale that has been established by the world's foremost authority on diamonds, the Gemological Institute of America.