A bezel is that slanted edge on the tip of a chisel. Angled edges on cut gems like diamonds are also bezels. The grooved ring that holds the crystal of your watch in place is called a bezel, too.
Bezels can also hold gems in place. If you've got a ring with a stone in it, the stone is likely held by prongs or by a solid rim — a bezel — that runs around the entire edge of the stone. If a prong gets worn down or bent, the stone can slip out, so a bezel setting might be a better choice for you if you’re catching lots of fly balls or kneading dough with your ring hand.