Wow, that was a truly good news - bad news situation for you the whole way! Kudos to you for your persistance.
I have no idea how to answer your last question, since I'm in the same boat you are - don't own one, and not enough experience to tell you what's the norm. I'll take a stab at it and say that the more expensive the pearls, the more likely that the choker was knotted. I think a stroll over to Google one of the links that talks about royal jewels would be in order...off I go.