Brasso. It works wonders for scratches. Get some brasso, a nice buffing cloth and if you have one, a dremel with a soft buffer head. If not, just do it by hand.

If you are scared, take it to a jewelry repair place and ask if they can do anything with it, lots of people have tried this and it runs from anywhere 5-10 bucks, and they basically buff the scratches out like they do with watches.