Princess Diana attends a dinner at the British Embassy in Washington, D.C. in November 1985. Terry Fincher/Princess Diana Archive/GettyPrincess Diana was last pictured in Queen Mary's Lover's Knot Tiara around 1991, the year before she and Prince Charles separated. The fairytale tiara then went unseen for many years, until Princess Kate dusted it off for a triumphant return 24 years later. Princess Kate was then popularly called the Duchess of Cambridge, and the tiara inspired by the Cambridge Lover's Knot was a thoughtful tribute to her title then. Despite her status as future queen, Princess Kate has only worn five different tiaras during her 14 years as a working royal.