Kate Middleton wears the engagement ring of Diana, Princess of Wales, as she poses for the media with Britain's Prince William following the announcement of their engagement Tuesday.

Britain's Prince William and his fiancée Kate Middleton pose for photographers during a photocall to mark their engagement Tuesday.

Britain's Prince William and his fiancee Kate Middleton pose for the media at St. James's Palace in London, Tuesday.

Britain's Prince William and his fiancee Kate Middleton arrive for a media photocall, media at St. James's Palace in London, Tuesday Nov. 16, 2010, after they announced their engagement.

Britain's Prince William and his fiancee Kate Middleton pose for the media at St. James's Palace in London, Tuesday.

A file photo taken on March 13, 2007, shows Britain's Prince William (R) and his girlfriend Kate Middleton on the first day of the Cheltenham Race Festival at Cheltenham Race course, in Gloucestershire.

Britain's Prince William, and his girlfriend Kate Middleton arrive for the first day of horse racing at the Cheltenham Festival, Cheltenham, England,Tuesday, March 13, 2007.

Britain's Prince William and his girlfriend Kate Middleton walk together at RAF Cranwell, England, after William received his RAF wings from his father the Prince of Wales

Britain's Prince William, left, walks with his girlfriend Kate Middleton after his graduation ceremony at RAF Cranwell, in Cranwell, England on April 11, 2008.

Britain's Prince William and Kate Middleton leave the wedding of their friends Harry Mead and Rosie Bradford in the village of Northleach, England, in this October 23, 2010, file photo.

Britain's Prince William and Kate Middleton, watch the England against Italy Six Nations rugby match at Twickenham stadium in London, in this Saturday Feb. 10, 2007 file photo.

Britain's Prince William and Kate Middleton leave the wedding of their friends Harry Mead and Rosie Bradford in the village of Northleach, Gloucestershire, England Saturday Oct. 23, 2010.