I have been metal detecting all over the world and during the last few decades I have a amassed a rather large assortment of tokens and medals. Most have been buried for some time and are crusted in dirt. For pocket change I put them in the tumbler for about twenty minutes and this removes enough of the crud to roll them and turn them into the bank. If I did this to the tokens and medals would this ruin any value they might have to collectors. Most I'm sure are common car wash and arcade tokens I'm sure but one or two might be of more interest if you could only read them. So should I tumble or not?