I've had my solitaire ring for two weeks, and the stone is moving around!!! It's from a reputable store, Birk's in Canada. I haven't bumped it into anything hard--I've been really careful! It's a platinum four-prong setting. I didn't have a diamond engagement ring, so my husband decided to get me one after four years. I was SO excited, and now I'm really upset!!! Has anyone else ever had something like this happen?