Finish is the technical language watchmaking uses to describe every surface treatment applied to case, dial, or movement. It is not mere accessory decoration: it changes how the piece is perceived under light, determines resistance to wear, and in certain cases certifies the construction level of the timepiece.
On the dial, variety is such that each term must be read with precision. The sunray brushed — or sunburst — is obtained through radial brushing that radiates from the center: the dial changes color at every angle. Fumé is a shaded variant, often on a silver plate, that creates depth without adding layers. Opaline is opaque and silky, quite different from polished and satin: if you confuse them, touch them under raking light. Dégradé is a color transition — from center to edges or vice versa — executed chemically or by hand. Grained reduces reflections and improves readability in difficult conditions. Lacquered is a layer of transparent varnish over a solid color base: traditional Japanese lacquer, for example, has a chromatic depth that no industrial process replicates. Lamé is vertical brushing that produces a velvety texture. Hand-hammered leaves irregular dimples that catch light in a way never identical from one example to another.
On the movement, finishes serve a historical function beyond the aesthetic. Côtes de Genève — parallel diagonal stripes on bridges and plate — originated as a technique to remove burrs from machining before modern optical inspection existed. Today it is a positioning signal. The snailed decoration, with concentric spirals, appears on chronograph counters and flanges: it is not arbitrary, it serves to give depth to small surfaces that would otherwise appear flat. Guillochage — including Parmigiani's Grain d'Orge — is geometric engraving via pantograph or hand turning: every error remains visible forever.
In terms of treatments, PVD and CVD are deposition processes in a vacuum chamber — physical the first, chemical the second — that apply ultra-thin layers of hard material to steel. They resist wear, but are not eternal: at contact points, especially on lugs and crowns, they begin to fail before the rest. Vapor-blasting is fine abrasive blasting with water that produces a uniform matte surface, pleasant to the touch and less marked by fingerprints than polished finishes.
The Poinçon de Genève is the only certification that includes finish as a binding criterion: hand-polished surfaces, chamfers, sharp edges. Simply declaring it is not enough — it is verified piece by piece.