The physical vapor deposition method PVD is used to vapor-deposit superhard films, and different coating types will produce different colors. Different coating colors can be divided into: titanium nitride TiN, titanium carbonitride/titanium carbide nitride TiCN, chromium nitride CrN, aluminum titanium nitride TiAlN/AlTiN, aluminum chromium nitride AlCrN, aluminum chromium titanium nitride TiAlCrN, TaCoN, Hitec, diamond-like carbon DLC, please refer to various coating pages.