I am not a member of this message board, but I thought it would be an interesting subject here as well.
The poster mentions that the Duchess was borrowing different tiaras at that period of time. However, I think I have seen the Duchess with this aquamarine tiara at a number of events. So I don't think it is borrowed. On the other hand, I would be interested to know which other tiaras worn by her that mighr be considered borrowed.