In watchmaking, carbon is not just one material: it's an entire family of technical solutions that share the raw matter but diverge radically in structure, manufacturing process, and mechanical behavior. Confusing them is the most common mistake I hear, even from people working in the industry.
The starting point is raw carbon fiber, filaments of carbon atoms bonded in crystalline structure. From there the paths separate. In forged carbon the fibers are randomly arranged in a mold, impregnated with epoxy resin and hot-pressed: the result is a composite with an unrepeatable marbled weave, each piece different from the next. Artya, Tissot with the PRX, and Casio Edifice use it. In unidirectional carbon all fibers run in the same direction, the laminate is more anisotropic but more predictable under axial stress. In Richard Mille's TPT carbon we reach extremely thin layers oriented at 45° to each other: to qualify as TPT the laminate must weigh less than 100 g/m², otherwise it's not TPT, just a fine laminate. Carbonium, used by Ulysse Nardin in the Freak X Gumball and by Romain Gauthier, starts from aerospace-grade fiber scraps and consolidates them into blocks that are then machined: the texture is richer and more irregular than traditional forged carbon.
On the coating side, DLC (Diamond-Like Carbon) is amorphous carbon deposited by PVD onto steel or titanium. It's not a structural composite: it's a hard protective coating, scratch-resistant, with that black finish you see everywhere now. High wear resistance, but if the case takes a violent blow the DLC can chip because it's rigid, not elastic.
The most interesting frontier I've followed in recent years is the balance spring in carbon. TAG Heuer developed the TH-Carbonspring via Chemical Vapor Deposition: carbon nanotubes grown in a controlled environment, infiltrated with amorphous carbon to close porosity. The collet forms during growth, eliminating a critical assembly step. The result is non-magnetic, lighter than silicon, impact-resistant. I don't yet know how robust it will be over time compared to a Nivachron spring, but the manufacturing approach is solid.
Then there are material hybrids: CarbonGold by Bulgari has combined rose gold and carbon fiber since 1993, Norteq by Norqain claims six times less weight than steel, LUM-CAMO by Bell & Ross infuses Super-LumiNova into the carbon matrix. Every brand has its own proprietary name. Behind almost all of them there's always the same basic pair: fiber plus resin, heat, pressure.