Hey Jeff, always a pleasure.
There was a thing on a TV car show where a part was placed in a tank of solution. Floating on the top of the solution was a decal of sorts. The part was pulled from the tank under the decal which stuck to the part and looked fantastic.
The idea is to replicate that process with fasteners that will look like cadmium when finished. Cadmium is dangerous to work with Cadplating is CdCN (cadmium cyanide),and it's possible that a substitution is out there that would be concourse correct and not rust under the washer.