Great concept! The smoke and diamond really work well together. There's something that doesn't quite sit right with the right side of the diamond, maybe a little more focus. It almost looks to me like the stone is not symmetrical.
I'm not really sure what's going on in this picture, but that might be a good thing for an advertisement because it's very eye-catching. The diamond looks great!
It kind of looks like a conversation between the stone and the smoke, which is cool. For a product shot, though, that may be confusing to a buyer. Nicely lit and exposed.