Good use of high key, very clean layout. The blown bit in the diamond itself might not be a good thing for a product ad, but the overall effect of the shot is very good.
the whites are a little blown out in the center of the ring, but i've heard lighting diamonds are one of the singlemost hardest (lol) things to light properly. so i'll give you alot of credit for at least attempting it, and pulling off a decent shot. good luck
Lighting seems very harsh, highly recommend diffusing to make the light a larger light source to make it more pleasing. Also light from the sides to prevent direct reflections to the camera.