The Greville Tiara (also called Boucheron or Honeycomb Tiara).

At her death Dame Margaret Greville left some of her jewels to Queen Elizabeth, the Queen Mother. The jewels remained in their boxes for several years as the King was unsure about accepting gifts from subjects. The Queen finally wore Mrs Greville's tiara for the first time in 1947. Later, it was altered by Cartier with the strict geometric line being broken up by the addition of diamonds on the top.