To be honest here....
OurCiel didn't really "steal" it. They both new he swallowed it, how else did they expect the ring to disapeer? That was a pretty big ring for a small throat like RealCiels throat.
And it would almost be impossible to poop it out really. Though throwing up may be a lot better option.
Though I would say that he did "intrude" into his stomach.
I thought it was Sebastian who get that ring? Or did I remembered it wrong? 'cos if he did then it would be easy for him to get it while he's asleep or perhaps already dead than revived? We keep getting twists in this story. So every option is possible hehe
It was OurCiel who took the ring from Ciel's stomach. See this image intro: http://2.bp.blogspot.com/-YuOHeADcPKY/V-0W7obBzJI/AAAAAAARIac/8JiUqPdQe8s/w1600/1.jpg Chapter 62, page 1. His hands are fool of blood and he has the ring in his hands
"Don't tell anyone I swallowed that blue candy." Real!Ciel had said this to him. "Who stole the candy from my tummy?" Was written of the wall before Our!Ciel and Sebastian got to the manor. No wonder Our!Ciel freaked when he saw that description.