You can clean sterling silver with aluminum foil, water and washing soda. Pierce the foil for better solution movement. Lay the foil in a tupperware sandwich-size container. Fill 3/4 with water. Add 2 tablespoons washing soda (not baking soda) and stir. Set your sterling silver in the solution until the oxide is released. 30 seconds or so. Then rinse and buff.
Do not use on silver that has marquisite or darkened designs (eg. lettering).