Thank you for those wonderful stills from the videos Baxter.
How very telling they are. The clasp with the two rubies is very clear, as is the larger pearl snap.
I have seen a number of photos showing QEQM wearing what I think is the necklace with the ruby clasp and then noticed that her brooch has a different coloured stone.
I suspect that HM did not worry about having a different coloured stone/s at the rear of her necklace, but I have never noticed her mixing different colours in the gems which could be seen from the front - but, as so many photos are black and white, I could be mistaken.