Why should you buy HRD / GIA certified diamonds?

A certificate indicates the quality characteristic of the diamond; the shape, cut, carat (weight) and clarity. In addition, it will tell all historical treatments, inclusions, proportion, and finish of the diamond. It has to be made by an independent, non-bias laboratory with a good reputation such as GIA or HRD. A diamond with a "home-made" certificate or with a certificate from an untrustworthy laboratory defeats the whole purpose. 

For investors it is even more crucial to have a certificate, it will create liquidity to your investment. A diamond with a high-level of details certificate can be more valuable than those with fewer details. For insurance purpose it is important to have a certificate. Nonetheless, an expert help is still needed and important. He will give you the details beyond the 4 C'S on the certificate. An expert will help you to see the beauty and brilliance of a diamond, a certificate will not be able to translate the scientific details into beauty. He would be able to help you to compare different diamonds and show you the most beautiful and brilliant diamond.