Sterling silver? That's an investment. I've found a few sterling silver pieces of jewelry in the recycling for a pretty penny after I polished them up. A good trick is to boil water, place tin foil on the bottom of the pan, add the knife with as much surface area touching the tin foil as possible, and pour baking soda into the mix. It removes the tarnish easily and dirt cheap. I've done it many times, but feel free to test it/research first.