All of our diamonds at BigDiamondsUSA are graded by a G.I.A. Graduate Gemologist, and a Diamond Grading Certificate is provided by United Gem Laboratory. Clarity grades are based on appearance after enhancement. United Gem Laboratory is an Independent Gem Laboratory located in Chicago servicing the local jewelry trade. We guarantee the enhancement process in the unlikely event the enhancement is altered we will re-enhance your diamond FREE for life. With every purchase BigDiamondsUSA provides a Retail Replacement Value Appraisal for your insurance company.