The Aquamarine Pineflower Tiara; made by Cartier. This piece originally belonged to the Queen Mother. It was an anniversary gift from her husband, King George VI of England. It now belongs to Princess Anne.
This is the famous Londonderry tiara. Its biggest claim to fame is that Lady Londonderry dropped it down the loo at Westminster Abbey during the coronation of Edward VII in 1902 and spent most of the ceremony trying to retrieve it.