sterling turns coppery

My sterling begins to look coppery if I tumble it for 20 or 30 minutes...and doesn't get polished no matter how long it runs. What am I doing wrong?

Stacy's Answer:

There could any number reasons why you're getting the results that you are. There are so many variables: type of tumbler you're using, the dish soap, water quality, the tumbling medium (i.e. stainless steel shot, walnut shells, etc.) If you're able to provide more specifics then I might have a better idea of what might be going on and how to remedy it.