Years ago here in England it was the rage to wear engraved silver
identity bracelets. As long as they were worn continually they
didn’t tarnish or discolour the skin. My son wore a silver chain with
a St. Christopher medal for years with the same result. So it seems
that continual wear does indeed keep the nasties at bay. In a similar
vein, I was once told that it is necessary to wear pearls frequently
in order to preserve their warm appearance - something to do with
skin oils I believe - but I’ve never been able to verify this.