"Normally the stones would have been returned to Rundells after the coronation, but in this case there is no sign that the delicately worked diamond sprays and crosses, a masterpiece of the new transparent style of setting, have been disturbed. Equally, there is no evidence that the King purchased the stones outright, so it could be that the bill was met by a discreet barter of old stones from George IV's extensive collection." https://www.rct.uk/collection/31702/the-diamond-diadem
