DLC; Diamond-like Carbon is a class of amorphous carbon material that exhibits properties similar to that of diamond. The coating is applied in a thin layer (1-4 microns thick) in a specialized vacuum chamber and deposited using a PVD Physical Vapor Deposition Process.
The resultant coating has a hardness of 2000-4000HV and in effect becomes extremely scratch resistant. How hard is this? The base 316 SST material which is generally considered very hard material is typically about 700HV, the DLC coating is 3-6 times harder than this.