Before buying a diamond ring, it helps to know the Four Cs—cut, clarity, color,...

https://hatton-garden-jewellers.co.uk/7-things-to-check-before-buying-a-diamond-ring

Before buying a diamond ring, it helps to know the Four Cs—cut, clarity, color, and carat—and how they affect what you’re paying for. Check for a GIA grading report number to verify quality