Content of metal in costume jewelry

I have several very nice pieces of costume jewelry. I do not know
the content of the metal used for the bands (rings). These have been
gifts. I would like to preserve the finish on these pieces, even
though the monetary value is not much, the memories attached are
valuable. Do you know what a person could apply that would look okay
or not be noticed at all? I checked with a hobby shop and they
suggested Future Acrylic floor polish. I am afraid to try this on
these pieces. Would it look to gunky or would it last? Can you
suggest something better? There is a stone involved, so if I spray or
dip it I would have to be extremely careful. Is there something I can
apply by brush? Any help you could give me would be much appreciated.

Thank you

Nina, a hypoallergenic nail polish is just the ticket.

I use it on the backs of costume jewelry because I am allefgic to
everything but ss and precious metals. It also will coat costume
jewelry surfaces from wear and damage. The only consideration is that
they be ABSOLUTELY clean of oil and ‘stuff’. And be prepared to
re-coat it now and then. I wouldn’t coat the stones.

Good luck with it!