Black in watchmaking is not a single color: it is a family of treatments, materials and finishes that produce profoundly different optical and mechanical results. Confusing PVD, DLC, Grand Feu enamel and Vantablack is a mistake you pay for at the workbench, because they behave differently under wear, light and time.
PVD (Physical Vapor Deposition) is the most widespread black coating. It is deposited hot onto steel or titanium in a vacuum chamber, forms a thin but hard layer, resists surface scratches and protects against corrosion. DLC (Diamond-Like Carbon) goes further: the deposited carbon mimics the crystalline structure of diamond, achieves surface hardness significantly superior to PVD and produces finishes ranging from matte to deep gloss. Both tend to show micro-abrasions over time on the sharp edges of the case, where the coating is thinnest. The difference becomes visible after years of daily use.
Black Grand Feu enamel is another universe. It requires up to thirty layers of pigment baked in the kiln one by one: each layer must cool before receiving the next, and every firing is a risk. Black is the most demanding color because every bubble, every crack, every unevenness stands out without mercy. The result is an optical depth that no physical coating replicates.
At the opposite end of the spectrum are ultra-absorbent blacks. Vantablack absorbs 99.965% of incident light, Musou Black 99.4%. Both eliminate almost all reflection, rendering treated surfaces visually flat in a disorienting way. Vantablack, however, is fragile: it does not tolerate direct contact. Musou Black is more robust and applicable to exposed components.
Black rhodium and black gold are chemical platings applied to hands and indices to create controlled contrast on the dial. Black gold is obtained by chemically darkening gold; black rhodium is a galvanic deposition. Both age differently from DLC and require maintenance in restoration.
Micro-arc oxidation is an anodic treatment used on titanium: it oxidizes the surface creating uniform and durable black, useful on movement components like tourbillon cages where weight matters as much as aesthetics.
From the workbench: matte black reduces reflections on the dial and improves readability in bright light — it was the criterion of British military specifications in the Second World War, and it has remained valid. Gloss black, on the other hand, shows every fingerprint and every scratch with the same ruthlessness as Grand Feu enamel.