According to Roberts (page 202) the diamond sautoir can be unhooked to form 2 necklaces and two bracelets. Some of the sections where the diamonds are linked can be seen in the photos on pages 202-3 and on page 204.
Unfortunately, I don't think that there is any record of The Queen wearing such a necklace - in public at least. Although the setting in the sautoir is different, such a necklace would be similar to her South African diamond necklace, which she may prefer.
on July 29, 2015, 5:12 pm, in reply to "