Acetone would remove any actual pieces of degraded rubber that might be still stuck to the coin, but the tarnish stripe left behind will not come off in acetone. Rubber is chock-full of sulfur, and it's this sulfur that has reacted with the silver to turn it black. Regular "toning" on a coin is caused by a similar reaction with atmospheric sulfur. Tarnish remover or "dip" will get rid of the stripe, but the end result will be a dipped coin.

Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis