I'll start one of the threads Nellie has suggested.
Last night just before bedtime I finally finished reading The Queen's Diamonds! Roberts ends it, just before the official Diamond Jubilee portrait, with beautiful pictures of the King Faisal and King Khalid necklaces. Both came from Harry Winston in New York. As I was falling asleep, it occurred to me that the 'mystery' necklace, which Roberts does not include in his survey of the Queen's diamond jewels, could have been from King Fahd, who visited London in 1987.
Is the Queen wearing the mystery necklace in this picture taken at the return banquet with King Fahd, or is it one of the previous necklaces from the Saudi kings? Does anyone have a better photo?
Is it known what the king gave her in 1987, and had she worn the mystery necklace before this visit? Could King Fahd have decided that giving the Queen a Harry Winston necklace was a tradition in his family that he should continue? Or is the mystery necklace something else altogether?