
Sterling silver will oxidize or "turn" color if you keep it sitting in your jewelry box or on your dresser. To properly care for your jewelry, I always recommend you put any pieces that contain sterling silver in a little ziploc bag. Put your piece inside the bag, take out any excess air; as that is what makes the silver oxidize, and close it securely.
I in

clude, in all my jewelry sales, a specially treated anti-tarnish strip that will help in keeping your silver shining like new but only if you keep it in the ziploc bag like you are supposed to do. Of course, there are also polishing cloths that will help you in maintaining your jewelry looking like the day you first bought it. At the right you can see what the anti-tarnish squares look like. Rather plain looking, I know, but they really work.
Those are the kinds of strips I put in my jewelry trays where I keep all my pieces ready for shows.