Unless you plan to hide your silver necklace in an airtight box in a dark closet, you should expect some tarnish. Exposure to perfume, body oils and even the air can cause tarnish. However, in cases of severe oxidation or rust, a few wipes with a silver polish cloth will not be sufficient. Treat rust by soaking and polishing the necklace to restore its lustrous shine. If your necklace includes jewels or precious stones, you need to remove them before soaking the silver. Consult a professional jeweler if the chain appears thin or has a pendant you cannot detach.
Cover a small plate with aluminum foil. If you prefer, use a disposable aluminum foil plate.
Sprinkle 1 tablespoon of salt and 1 tablespoon of baking soda in the plate.
Pour a small amount of heated water into the plate. Do not use boiling water. Use a teaspoon to combine the salt, soda and water. They should dissolve together completely.
Place the necklace in the solution. Allow the necklace to soak in the soda/salt bath for a few minutes. You may notice a sulfuric, rotten-egg smell. This is a result of the chemical reaction between the rust and the solution.
Remove the necklace from the bath. With clean hands, rinse the necklace under cool water. Pat the jewelry clean with paper towels. Follow up by rubbing the necklace with polish cloths.