@thejessiekirk@ohai.social
We used toothpaste. It is a gentle cleaner that will limit the damage to the metal.
Brasso is aggressive and continued use will dissolve the plating on the coin. Coke is even worse, leave a coin in coke for a month and all the plating will be removed. (I think there was a hack back in the day to make a 2p look like a 10p, but the construction was changed to stop that).