I clean my silver coins with simple electrolysis. Just find an old AC adapter, separate the 2 wires, strip a bit of the insulation off the ends, and attach a couple small alligator clips to each wire. You'll also need a small plastic container (tupperware, butter tub, etc), a sterling silver spoon, and a little baking soda or salt. Put a little baking soda or salt in the container and mix with warm water. Bend the spoon and hang the bowl end over the container and into the water. Connect the negative side of the AC adapter with the spoon, and the positive terminal to the coin (or ring). With both spoon and coin in the water (but not touching!), plug the adapter in and you'll start to see the coin fizzing a bit. Let this run for a couple minutes at first, then unplug the adapter and take the coin out. Wipe it between your thumb and forefinger and see how much (if any) of the black tarnish comes off. Keep repeating the process until you get it cleaned like you want. For stubborn stains you may need it to cook for quite a few minutes. You can also use a baking soda paste to help in the process, but I prefer not to to this for coins unless its a common one. Otherwise, it'll get that fakey-looking shine. But for a ring, it shouldn't be a problem. Anyway, give it a try and let us know how you made out. Good luck!