Bilbo´s treachery

[Zigûr]

Originally Posted by Galadriel55

EDIT: Just to point out, at this point in the story Gandalf isn't that well-versed in Ring-lore. I don't have FOTR with me, but from what I recall he made the trip to Gondor's library only after Bilbo returned home to the Shire - perhaps even after Bilbo's 111th birthday. The queer look he gives Bilbo after his glorified tale of his escape from the goblins is very much explicable just by the extravagance of the tale, and suspicions specific to the nature of the Ring are quite unlikely.

Yes, according to the Tale of Years Gandalf visited Minas Tirith and read the scroll of Isildur in 3017.

That's not to say that he was ignorant of Ring-lore before that, of course, but it had been Saruman's area of expertise, not his:
"The lore of the Elven-rings, great and small, is his province. He has long studied it, seeking the lost secrets of their making; but when the Rings were debated in the Council, all that he would reveal to us of his ring-lore told against my fears." [The Shadow of the Past]