Sterling silver contains copper, so it will naturally tarnish over time. Some jewelry and silver look best oxidized, while other pieces are better when highly polished. While there are many chemical methods to polish silver, you can clean tarnished silver with relatively environmentally friendly baking soda, hot water and tin foil.
Line a vessel large enough to hold your tarnished silver with tin foil. You can use a dish or a porcelain sink.
Place the tarnished sterling silver on top of the foil. Sprinkle baking soda over the sterling silver. Pour boiling water into the vessel.
Allow the sterling silver to soak for a while until the tarnish begins to float off the piece.
Turn the piece over so that the foil touches multiple sides. Soak again.
Rinse the baking soda off in fresh water when you are pleased with the polish.