harryg
We don't know what is on the coin so it is difficult to say. Looks to be a relatively modern coin so no value will be diminished if a cleaning attempt is made. I don't like recommending cleaning any coin until you are aware of the potential consequences. Having said that, Acetone or nail polish remover containing acetone may work as it is safe to use on all coins without harming them. Let it soak for a while then gently rub with a very soft cloth.
I assume this is the coin in question?
N#3362
Ok, thank you I will try that. And yes, that's the right coin.
