A bezel is a band of metal containing a groove and a flange (i.e. projecting lip) holding a watch crystal or gemstone

Gemstone

A gemstone or gem is a piece of mineral, which, in cut and polished form, is used to make jewelry or other adornments...

 in its setting. This was the earliest method of setting

Stonesetting

Stonesetting is the art of securely setting or attaching gemstones into jewelry. Stonesetting can also be used in referring to setting a stone or orb believed to have magical properties into a staff.-Cabochon and facet:...

 gemstones into jewelry. An extension of the word used in this sense can refer to a rotatable rim on a clock or watch used to indicate certain data such as elapsed time.

Method

The bezel is shaped into the size and shape of the gem and then soldered into place on the metal of the jewelry. The prepared stone is then placed into the bezel and the metal is pressed down over the edges of stone, locking it into place.

A cabochon

Cabochon

A cabochon , from the Middle French caboche , is a gemstone which has been shaped and polished as opposed to faceted. The resulting form is usually a convex top with a flat bottom. Cutting en cabochon is usually applied to opaque gems, while faceting is usually applied to transparent stones...

 stone, a gemstone that is not faceted, usually relies on the shallow angle

Angle

In geometry, an angle is the figure formed by two rays sharing a common endpoint, called the vertex of the angle.Angles are usually presumed to be in a Euclidean plane with the circle taken for standard with regard to direction. In fact, an angle is frequently viewed as a measure of an circular arc...

 cut into the side of the stone which helps the metal to stay in place. With a clear facet

Facet

Facets are flat faces on geometric shapes. The organization of naturally occurring facets was key to early developments in crystallography, since they reflect the underlying symmetry of the crystal structure...

ed stone, such as a diamond, a shallow groove is cut into the bezel itself. The girdle or widest part of the gem stone is placed in the bezel, which is then pushed down over the girdle. The pressure of the bezel over the edge of the diamond keeps it in place.

Bezel settings for diamond rings are also called rub-over settings; they have a diamond completely surrounded by a precious metal band which fastens the diamond securely into place. Bezel settings use a type of elevated collar which wraps the rim of the diamond in a complete metal edging. This type of diamond rings setting is the most secure fastener for the stones. The bezel setting also protects the diamond better than other types of settings, such as the prong setting. A flush

Flush

Flush has several meanings:* Flush , to become markedly red in the face and often other areas of the skin, from various physiological conditions* Flush , a hand in card games** Flush , a hand in poker...

 setting for diamond rings is a variation on the rub-over or bezel setting. In the flush setting, the stone is placed into an opening and affixed at the bottom of the stone. The top of the diamond is extended above the base.

Advantages

Diamond rings with bezel settings give the rings a more elegant, understated and streamlined appearance than the prong setting

Prong setting

Prong setting refers to the use of metal projections or tines, called prongs, to secure a gemstone to a piece of jewelry. A prong setting is one component of what is known in the jewelry business as a head, a claw-shaped type of binding that is welded or soldered to a jewelry item in order to...

. Another advantage of the bezel setting is that the diamond is better protected from accidental rubbing or blows and less likely to allow the diamond to scratch or mar something it comes in contact with. The bezel setting is more secure, so the diamond is less likely to be dislodged by the wearer's activity.

Some expensive watches have diamonds in bezel settings.