Silver plating is also common in RF voodoo work. It improves the performance of any resonant enclosure like a cavity or interdigital filter.
Ed
A cautionary note:-
Not all silver plating is the same.
The stuff used in Commercial plating shops for medals, trophies, & domestic silverware is optimised for appearance, ease of polishing, & durability.
To this end, various impurities are added to the plating solution.
During the early years of Radio, this was not the case, & ordinary silver plating was quite pure, so that the
promised decrease in losses actually occurred.
By the 1950s, the Commercial mix had changed, but "silver plating to decrease losses" was still "received wisdom" among RF folks.
In the later years of that decade, two EEs published (in the "Telecom Journal of Australia") the results of their testing with plain copper-v- ordinary commercial silver plating.
They found that the former was less lossy at RF.