Sensitivity of the blackening
PVD coating is one of the highest quality and most durable coatings, and is abrasion-proof, unlike electrolytic coating (e.g. gilding). The high quality is obtained by plasma coating, where the material is applied as a plasma jet and forms an inseparable connection with the steel ("surface alloy"). Because it is harder than steel, a PVD surface is more scratch-resistant, for example, but certainly not indestructible.