I don't think there's a more appropriate thread for this, so I'm posting it here.
I stumbled on
this photo of Princess Tatiana Radziwill from 1964 wearing Queen Sofia of Sweden's pear spike and star tiara! Maybe it was loaned to her for an event celebrating the wedding of Princess Anne-Marie and King Constantine II in Copenhagen that year.
The tiara currently belongs to Princess Benedikte of Denmark and has been loaned to Queen Anne-Marie at least once.
Image credit:
IMAGO / United Archives International