I jumped the gun too soon. I found an old thread where Boris idetified the provenance of the necklace.
"The necklace (with matching earrings, obviously) was given to Queen Elizabeth II by King Hussein in 1966 and first worn during a 1984 state visit to Jordan. "
There was also some discussion that the second stones were amethysts (as opposed to sapphires).
So it looks like just the brooch questions is still outstanding.
Cheers! Bryce
Edit - Thanks Manuel --Previous Message-- : to my knowledge this necklace was a present : from the jordan king : :