What a mystery we have. Like Franck I doubt if the two elements with the sun ray design in diamonds have been added to the necklace. That design matches the upper element in the earrings, while the bottom element in the earrings matches the pendant drops. I suspect that this was the original design and was intended to add interest to the necklace without having to use a large number of bigger diamonds. A string of large amethysts surrounded by small diamonds would not be as impressive and the earrings would not fit with the necklace. The necklace as photographed on QEII is longer than what she normally wears. If she had wanted to lengthen an existing necklace using one element would have been sufficient and, if that were done, then I suspect HM would have used it as a clasp so as not to change the appearance of the initial design. Unless we can see photos or paintings of other royal ladies wearing this necklace, we may never know with certainty how it was initially set. In the photos supplied by Joye the Duchess of Kent and the Queen Mother are wearing different brooches (and I suspect we can see a shadow rather than pendant drops under the brooch worn by QEQM). The brooch worn by the Duchess is commonly identified as part of the demi-parure so I think we can identify 2 of the brooches. Merlin, I too would be delighted to see any photos, if you can post them.