A knurled bezel is a watch or jewellery bezel whose outer surface is finished with a regular pattern of ridges or notches, produced by rolling, cutting or coining the surface against a knurled tool. The pattern provides both decorative texture and improved grip when the bezel must be turned by hand, as in dive watches and chronograph timing bezels. In jewellery, knurled bezels are encountered as decorative finishes on ring shoulders, on pendant cases, and on the outer rims of bezel-set stone mountings.

Patterns and production

The principal knurled patterns in jewellery and watchmaking are straight axial knurling, in which fine ridges run parallel to the bezel's axis; diagonal or angle knurling, in which the ridges follow a single helix around the rim; and diamond or cross knurling, in which two opposed helices intersect to form a regular grid of small pyramidal points. The pattern is produced either by rolling the bezel against a hardened steel knurling wheel under pressure, in which case the ridges are formed by displacement of the surface metal, or by cutting on a lathe with a knurling tool that traces the pattern as a series of cuts. Cast knurling, used in volume production, replicates the pattern from a master rather than producing it directly on the workpiece.

Use in watchmaking and jewellery

In watchmaking, the knurled bezel is most strongly associated with the dive-watch genre, where the rotating timing bezel must be turnable by hand under water and with gloved fingers. The Rolex Submariner, the Omega Seamaster Diver and a long list of comparable references all carry knurled or coined bezels of various patterns. The fluted bezel of the Rolex Datejust, while not strictly a knurl, is a related decorative form. In fine jewellery, knurled bezels appear on antique-style mountings as a Georgian and Victorian decorative treatment, and on contemporary work where a textured rim around a bezel-set diamond or coloured stone provides visual contrast against the polished surfaces of the gem and the shank.

Wear and restoration

Knurled finishes wear with use. The high points of the pattern lose definition first, particularly on rings and watch bezels worn daily, and after several decades of wear the original knurl may be visibly softened or partially worn smooth on the most exposed faces. Restoration of a worn knurl on a watch bezel typically requires replacement of the bezel rather than re-knurling in place, since the original ridges cannot generally be cleanly re-cut without removing more material than the design tolerates. Jewellery knurling can be restored by hand-cutting at the bench, but the labour is substantial and the result tends to read as restored rather than original.