Looking at purchasing a round diamond solitare 2.08ct, SI2, H in color, and very good cut. The problem is that the diamond is not certified! Do I take the word of the dealer who is very respected and just get it apraised by an outside apraiser, or do I need to get it certified? He is asking $7,700 for the diamond set in a platinum setting. It this a good deal? HELP!!!!!!