5. Diamond certificate
Every diamond you buy is accompanied with a diamond certificate that describes all features of the gem in greater detail. There you will find information related to color, cut, quality and carats. Demand to give you the document so that you could be sure that you are buying a genuine diamond. Ask for AGS and GIA certificates.
6. Observation of the diamond
People who deal with diamonds know that black background enhances the sparkle. Use white background instead. This is the only way to find out how good the diamond is. Avoid following the advice of jewelers and vendors since they may sometimes be misleading.