The Duchess of Cambridge arrived at Buckingham Palace wearing a Royal family heirloom and it is believed to be the first time she has been seen in public with a sparkling headpiece since her wedding in April 2011.
Kate attended the diplomatic reception hosted by the Queen at Buckingham Palace alongside husband the Duke of Cambridge.
The Duchess wore an evening gown by Alexander McQueen.
The tiara, loaned by the Queen according to Kensington Palace, is the Lotus Flower, or Papyrus Leaf Tiara.
It was the Queen Mother's fanmotif tiara made from one of her wedding gifts in 1923 - a necklace of a Greek key pattern with pendant diamonds and pearls given by her husband, the future George VI. It is crowned by floating diamond arches and studded with two pearls at the base and a central top pearl.
The Queen Mother was often seen wearing it for formal occasions and gifted it to Princess Margaret who also chose to wear it when she attended the same annual event in 1958.
Princess Margaret's daughter in-law, the Hon Serena Stanhope, is understood to be the last person to wear it in public on her wedding day to Viscount Linley in 1993.
More than 1,500 guests attend the annual reception at which the Queen entertains the capital's diplomatic community.