My daughter gave me a set of scratch brush pens at Christmas. They are made by Pixiss & they work great. The set includes soft steel, soft brass, fiberglass & stiff nylon. The brass does not scratch a Nickle or a copper Cent and gets the crud & discoloration off very well without damaging the detail. The fiberglass further cleans & smooths the coin. It also buffs off the tarnish on non collector silver coins. Very reasonably priced. I have struggled for years to clean my dug coins decently. These pens seem like magic! I also received a Digital Microscope that also is a great addition. It has side light LEDs as well as direct. Easy to use, gives a great view and can take photos.