Usually black, flat dark earth or grey, a coated finish reduces the reflection and glare while reducing wear and corrosion. However, ALL coatings can be scratched off after continuous heavy use, and the blade would have to be re-coated. Generally the harder the finish, the more resistant to wear and the more expensive to add to a knife. High-quality finishes are bonded electrically, chemically or thermally to the surface as opposed to a simple drying paint-like coatings. High-end coatings like DLC (Diamond-Like Carbon) require that the blade goes to a specialty coating facility for PVD (Physical Vapor Deposition) application in a vacuum environment. Interestingly, before being coated most blades receive a blasted finish to have maximum adhesion surface area. Coatings can prolong the life of a blade (especially with carbon steel) by preventing corrosion or rust. Quality coatings add cost to a knife but provide more corrosion resistance, less reflection and require less maintenance.