In the movement as in the case, finishes are not decoration added afterward: they are proof of how much time and human hand have gone into a piece. I've disassembled enough calibers to know that a well-executed finish can be recognized by touch before you even look at it.
On the movement, techniques divide roughly into two families. Linear finishes — Côtes de Genève, traits-tirés, Glashütte stripes, Moser double stripe — are parallel striations obtained through directional abrasion on plates and bridges. They give optical rhythm and capture light uniformly. Circular finishes — perlage, circular graining, circular brushing — work through rotation: perlage in particular is a pattern of overlapping microcircles obtained by rotating a spherical tool over steel. You often see it on internal plates, where the eye reaches only with a loupe. Its presence even where unseen is the difference that matters.
Anglage — also called biseau or bevelling — is the chamfering of the edges of bridges and plates. When done by hand, the sloped edge is then polished to a mirror finish: it's the detail that distinguishes an Élaboré caliber from a Standard one, and in movements with Poinçon de Genève certification it becomes a formal requirement. The Roger Dubuis RD515 declares sixteen distinct finish types on a single caliber. The Greubel Forsey Hand Made 2 shows five artisanal finishes simultaneously on the same surfaces: frosted, black-polished, straight-grained, polished flanks and chamfers with olive-dome rubies set in gold slots. These are extreme cases, but useful for understanding where the ceiling is.
On the case, the language changes but the principle doesn't. The three basic finishes — polished, satin-brushed and brushed — combine to create visual contrast and three-dimensionality. A fully polished case is rare and difficult to maintain. A fully satin-brushed case is subdued but flat. The mix between the two, when designed rather than accidental, says something about the maker's intention. Coating techniques like PVD and CVD add color and surface hardness without altering geometry, but they don't replace a mechanical finish: they prepare it.
The Swiss classification Standard / Élaboré / Chronomètre concerns precision and finishes together. Élaboré includes blued screws, snailed wheels, gilt engravings: it's an intermediate grade that justifies a mid-to-high price without requiring certification. Not all brands declare it explicitly, but those who do — like Sellita with the SW210-1B Élaboré variant — are saying something verifiable.