Use very fine steel wool to buff it up a bit, and then tumble it. The steel wool will remove a little bit of the ox but still leave it in the nooks and crannies.

Meenu,
If you have a tumbler, throw your jewelry into it - the jewelry will be polished to a shine, but unless you actively work to take the 'black' off, it will stay on the piece. This way, you can get shiny black! I've gotten good results with a leather buff on my Dremel, too.
BTW - I don't use steel wool - it gets into everything and is literally painful if the teensy fibers get on your clothes. I use scotch-Brite pads meant for washing dishes. These are abrasive, but you can see the fibers,(they are green) and they don't get into everything. Steel wool fibers in pickle are a nightmare - they can cause plating. The cheap versions of these from the Dollar store don't work - it has to be ScotchBrite pads.
Hope this helps, Perri

I polish with a silver polishing cloth or jewelry polishing cloth..........it makes it nice and shiny and removes the grit..........makes nice highlights too.