Forgive me for another "Gandalf's Knowledge of the One Ring" Post
Hello!
I know there are quite a few posts on the subject of what Gandalf knew when regarding the nature of the One Ring. However, I was doing another re-read of LOTR and one particular passage kind of struck me. For reference, here are a few relevant dates.
TA 2850 - Gandalf enters Dol Guldur, death of Thrain II (Gandalf obtains from him the Secret Key of Erebor, and the map)
TA 2941 - Bilbo finds the One Ring, White Council drives Sauron from Dol Guldur, Battle of Five Armies
TA 3001 Bilbo's 111th Birthday Party and departure from The Shire
TA 3018 Gandalf returns to The Shire, Frodo and company depart for Rivendell
In TA 3018, Gandalf returns to the Shire and has a discussion with Frodo about the Ring. He gives some background and Frodo asks "How long have you known all this?"
Gandalf's reply was interesting to me. He says that "a shadow fell on my heart then" with regards to learning of Bilbo's ring in TA 2941. So, right after Bilbo found it.
Gandalf also says "I wondered often how Gollum came by a Great Ring..." This is key, because earlier, Gandalf specifically talks about the difference between the minor Rings and the Great Rings. The Great Rings being the Nine, Seven, Three, and the One, of course.
This at least hints that Gandalf knew that Bilbo's ring was a "Great Ring", and thus one of the 20 Rings of Power, which I'm assuming are the same things (this might be the weakness in the whole line of inquiry, I admit).
Even by 2941, when Bilbo finds the One Ring and Gandalf begins to have misgivings, he must have known that at least the Nine and the Three are accounted for. Potentially, he may have thought that Bilbo's Great Ring could have been one of the Seven, but even so he had, by that time, already have learned that Thrain's ring was taken from him in Dol Guldur (TA 2850). One can reasonably assume that at this time Gandalf knows or at least suspects the fate of the other Dwarven Rings (taken, consumed by dragons, etc.).
Ok, so here's the question: Given that in TA 2941, Gandalf suspects that Bilbo's ring is a "Great Ring" and given that Gandalf had at least a reasonable idea of the fate and/or disposition of all the other Great Rings / Rings of Power at that time, why WOULDN'T Gandalf immediately jump to at least the possibility that Bilbo's ring was the One Ring? I mean, it would have to be either the One or some random ring of the Seven, right?
(Disclaimer: I know that LOTR is just a story and that Tolkien wasn't perfect and he left a lot of loose ends we love to discuss. :) But this whole series of explanations by Gandalf in Fellowship of the Ring made me curious.)