Good guys of LOTR clueless?

[gorthaur_cruel]

Sorry to top an old thread, but I discovered something new. Until now, I believed that Gandalf's actions were perfectly justified in not seeking the truth about Bilbo's ring. I assumed that he believed it to be one of the lesser rings, which is totally acceptable. However, Gandalf knew that Bilbo's ring was one of the twenty Rings of Power.

"I wondered often how Gollum came by a Great Ring, as plainly it was - that at least was clear from the first."

We know that "Great Ring" is another name for "Ring of Power", the twenty famous ones. Now, shouldn't Gandalf have been "professionally interested" and wondered which ring this was? He also said that the Rings of Power were perilous to mortals, so he should've felt anxiety for Bilbo. Anyway, he knew that it was not one of the Three or Nine, and most likely not one of the Seven. By pondering this, he should've remembered that only the One Ring (out of the Great Rings) had no mark. Thus, he should've figured out that Bilbo had Sauron's precious decades before he did in LotR. Heck, if I had Gandalf's knowledge, even I would have. He knew it was a Ring of Power...that alone should be reason enough for Gandalf to investigate it, shouldn't it?