Freezing and ice can push the stone out of men's rings, especially if the band is wide. If the band is wide and thin at the bottom, freezing can split the band right at the bottom. Doesn't affect ladies rings, band is too narrow. So if the stone is missing from a man's ring it is still in the hole. Someone told me about this phenominon years ago. I've found two rings that this happened to. Just like ice will split a steel water pipe.