Silver as a colour is a problem of surface rather than of pigment, and it is the reason there is far less surviving silver in old art than there once was.
There is no good silver pigment. Grey paint does not read as metal, because what makes a metal look metallic is a specular reflection that changes as the viewer moves, and a matte pigment cannot produce that. The only way to get silver onto a surface was to put silver on it: silver leaf, beaten thin and laid on a prepared ground, or shell silver, powdered metal in a binder, applied with a brush.
Silver leaf tarnishes. Exposed to air and to the sulphur compounds in it, the surface forms silver sulphide and turns first yellow-brown and then black. Gold leaf does not, which is the whole reason gilded medieval work still looks gilded and silvered work of the same date frequently looks like a dirty grey stain. A great deal of what now reads as a damaged dark passage in a panel painting or an illuminated manuscript was originally bright silver.
Workshops knew this and worked around it. Tin leaf was cheaper and tarnished less, and was often glazed with a yellow varnish to imitate gold. In East Asian lacquer, silver powder was used within a sealed lacquer surface that protected it.
The lunar and nocturnal symbolism recorded in the traditions therefore rests on an appearance that was always temporary. Silver in use is a colour that has to be maintained, which is itself part of what it came to mean.