This is really intriguing, thank you Ursula!

Are you able to share with us the evidence you have that the individual elements existed separately prior to being assembled on a tiara frame? I had always assumed that the tiara was constructed to be as versatile as possible and that all the elements were made at one time. But, of course, that was an assumption.

I saw on your site that you have an image of a handwritten description of the tiara https://royal-magazin.de/england/westminster/pearl-tiara-westminster.htm Is this from the firm which assembled the tiara? Is it dated?

Somehow I doubt if the Roseberys would have owned these pearls. If they were Rosebery heirlooms, it seems odd that they were not described with the other family jewels in the list of the wedding gifts.