I've been interested in the recent comments about whether the Ring induced Bilbo to take the Arkenstone and give it to Bard and the Elvenking. I think it quite unlikely; because Gandalf did not mention it in his later conversation with Frodo about the Ring and Bilbo.
When that happened, Gandalf discussed the Ring's influence on Bilbo in terms of the latter not telling the truth about how he got it, i.e. his initial explanation was that Gollum gave it to him due to the former having lost the riddle-game, and him later behaving like Gollum, saying that the ring was his 'precious'.
Nowhere did Gandalf refer to Bilbo taking the Arkenstone as an example of the Ring's influence. As I have mentioned before, Bilbo had an arguable case that the stone was the fourteenth share of the hoard he had been promised by Thorin and Company, and that he was entitled to pick and chose his own fourteenth, which he had done, giving the stone to others.
