Movement finishing is not a secondary ornament: it's the most direct measure of constructive care in a caliber, independent of complications. I've disassembled enough pieces to know that a well-finished movement resists time better — treated surfaces collect fewer debris, chamfered edges reduce micro-fractures under stress. Aesthetics and function don't separate easily here.
The most common surface decorations are Côtes de Genève — wavy parallel lines engraved on the main plate and bridges — and perlage, a motif of overlapping circles obtained with a rotating tool applied by hand to each point. Both frequently appear together on the same caliber: Côtes on wide surfaces, perlage on less visible internal surfaces. Glashütte Stripes follow the same principle but are characteristic of the Saxon tradition: more pronounced parallel grooves, precise visual identity of that manufacture.
Anglage — also called chamfering — is the working of internal and external edges of steel components: first beveled at 45°, then mirror-polished. On a complex caliber you count hundreds, sometimes over a thousand, internal angles. Each requires a manual pass. The result doesn't change function, but immediately reveals whether the person who assembled the piece had time and skill. Black polishing — or poli miroir — is the extreme form of this polishing: a surface so flat and reflective it appears black without direct light. It's difficult to achieve and difficult to maintain over time.
Snailing consists of concentric grooves applied to wheels: semicircle after semicircle, it creates a spiral effect. Soleillage — or raying — is instead radial, with furrows radiating from center outward like rays. Colimaçon is a helical variant of the same concept, often used on the barrel wheel.
On galvanic coatings, rhodium provides corrosion resistance and a cold-white appearance; 24K gold plating — or variants like the 5N treatment that shifts toward pink — changes the chromatic tone of the entire plate. The élaboré level in Sellita movements indicates intermediate finishing, above raw but below chronometer standard; soigné is an analogous qualification used by other suppliers, with blued screws and polished chamfers included in the package.
Côtes de Bethune deserve separate mention: De Bethune developed a decoration of its bridges that doesn't replicate Genevan waves but defines autonomous visual identity — one of the few cases where a manufacture created a recognizable aesthetic vocabulary at a glance.