Couple of things about this, wasn't going to type them on the Xbox messaging thing!
Have you dropped one ring, so you only have one in your inventory?
Are these rings removed from you when you go to gaol? I always thought stolen property was returned to the owner, thus giving you the chance to do it again.
As I mentioned last night. There's been a few cases where in order for the quest to complete, or advance, I need to start a discussion about the quest again. An example to this is a quest I did was regarding a missing daughter. I found her, returned her to her mother, but the quest was still ongoing. Spoke to the daughter, spoke to the mother, still nothing. It was only after I'd 'waited' for 24hrs, spoke to the mother again about her daughter, when she asked if I'd found her. (Silly cow had her daughter in front of her, but still she asked!!). It was when I said "Yes", that the quest completed.
I think there's a few errors of logic in the game mate so keep trying, I'm sure you'll get to it.