It's a cubic zirconia. As a former jeweler it's obvious as hell. If it were a real diamond of that clarity your looking at 10+ grand. That or it's moissanite. I'm tossed up between CZ or the later. Going back to look gag I'm going with moissinate. Ladies pro tip for you. If you take your ring and place it on a newspaper and can clearly see words through the stone it's not a diamond. It'll be cubic or moissinate.