All that I know about the necklace in the first photo is that Vincent Meylan mentions it in his book on Christie's, and noted that it was reputed to have belonged to Marie Antoinette. Obviously the Queen would have owned more than one set of pearls, but unless jewels have remained with the one family known to have inherited jewels from Marie Antoinette's daughter, I suspect that proving provenance would be difficult.
I am eagerly waiting the release of Vincent Meylan's forthcoming book. What a treasure trove that will prove to be! And, hopefully, it will solve a number of queries about the jewels of the Queen.