I'm interested in what happened to this necklace. It is not in the list I have of crown jewellery that came from the Twinning papers which is a bit odd as a number of other jubilee jewels are included. The last wearing I am aware of is by Queen Alexandra:
George V and Queen Mary seem to have kept other commemorative jewels that Queen Alexandra had as personal property (for example leek and PoW feathers brooches), so it seems logical that they would have obtained this for the crown collection. But I don't recall seeing a photo of QM wearing it, and we know QEQM and QEII didn't really wear / favour sautoir style of necklaces as Queens, so it could have been locked away unworn all this time. I would have thought that it would have been a suitable candidate for Hugh Roberts to include in his The Queens Diamonds book but he didn't, although other historic jewels also weren't included like the cockade brooch.
I'm hoping this jewel is locked away safely in Buckingham palace waiting for a future wearer!