Silver ring and Hydrochloric acid!?

I've heard that if you put some sodium carbonate (not bicarb) and a ball of alfoil in a pot of boiling water and stick your silver jewellery in there, then it will restore it to its former glory and the alfoil will turn black... I don't know how accurate it is, but your other option is to just wait for the AgCl2 to come off over time.