Silver plating is listed under composition, but there is a chemical process that was commonly used to add a very thin layer of silver to base metals that does not involve electrolysis called silvering.
Here is one example, but there are many others:
My inclination would be to add this as a new technique since the process adds very little silver to the composition, sort of like a colored coin.
A similar addition for silver gilt (vermeil) would also be helpful.