ETYM From an old form of French biseau sloping edge, prob. from Latin bis double. Related to Bi-.
A sloping edge on a cutting tool.
1. A rim that holds a transparent covering (as on a watch, clock, or headlight) or that is rotatable and has special markings (as on a watch).
2. The oblique side or face of a cut gem; specifically; the upper faceted portion of a brilliant projecting from the setting — see brilliant illustration.
3. A usually metal rim of a piece of jewelry in which an ornament (as a gem) is set.

Oblique side or face of a cut gem
Sloping edge of cutting tool; edge and facet of cut gem; flanged groove holding watch- or clock-glass

In arcade games, the bezel refers to the glass located around the monitor. It is often silk-screened with artwork relating to the game. See also arcade game.