Heat water in the microwave for 1 or 2 minutes.
Cut a piece of aluminum foil that roughly covers the bottom of a small bowl (like a cereal bowl).
Pour hot water into bowl. Place salt, soda, and dishwashing liquid into bowl. Place jewelry on top of foil and let it sit for 5 to 10 minutes. Rinse jewelry in cool water and dry jewelry completely with soft cloth. Discard solution after use and make a new batch next time.
According to wire-sculpture.com, "this works well for gold-filled, brass, german (nickel) silver, and sterling silver. I have even cleaned jewelry with freshwater pearls, shell cameos and mother of pearl with no problem.". DO NOT use on brass , bronze or copper.