I use Liver of Sulfur to artificially age (oxidize) the jewelry. Picture #1 shows what is looks like. It's very smelly stuff (like rotten eggs) that you dissolve in water. Gross green huh?
Picture #2 shows before and after the oxidation. Drop the silver in, wait a few minutes, then watch the magic happen! It comes out black and dingy, but after a little polishing - very cool!
Picture #3 - finished product!