All watch parts ( the middle case, the case back cover, crowns and fixed bezel) are sandblasting to get a matt silver surface with some grained texture. The sandblasted process is basically to projecting grains of sands to the stainless steel.
Once the watch surface is sandblasted, some pieces of the mass production are black coated by PVD process (Physical Vapor Deposition)
We offer to versions: silver finished (sandblasted only) and PVD finished (sandblasted plus PVD after)
The difference is the PVD processing to get the matte black color at the PVD versión once the surface is sandblasted.