protective paint for coins I have an antique silver coin that I was planning on displaying on a ring, and  I was wondering if there was a protective paint that I could put on the coin.  The paint needs to be scratch resistant, protect the coin from water and oils, and needs to be able to be removed from the coin without damaging the coins value.  I do not need the paint to protect the coin from tarnishing just to protect the coin from normal wear.  I haven't been able to find anything myself and I am not a coin expert so I was hoping a coin expert could help me with this, thank you.
Would you be happy to occasionally re-apply if the coating chipped? Clear nail polish would work in that case, and a soak in acetone won't harm the metal but would completely remove the polish.