It's been two years since Kate Middleton wore a sparkling tiara at the Royal Wedding, and while pulling up to the the Diplomatic Reception on Tuesday night, the Duchess of Cambridge once again adorned her head with a jeweled crown, the Huffington Post reports, the headpiece thought to be the Papyrus Leaf Tiara that belongs to Queen Elizabeth II.

If it is indeed the Papyrus Leaf Tiara that Middleton wore, that means it originally belonged to the Queen's mother, who was photographed wearing it circa 1930, before it was lent to Princess Margaret in the early '90s. While Middleton is not technically a princess, the beautiful piece certainly elevates her air of royalty, not to mention tiaras are mandatory for state banquets. Middleton also wore a glittery white Alexander McQueen dress and matching earrings that complemented her jewels.

The Diplomatic Reception was hosted by the Queen herself in Bentley, the capital to her official residence, as Hello! magazine reports, in which the 87-year-old monarch met with every member of the London Diplomatic Community, including 172 foreign ambassadors.

The reception, however, is just one of the many events Prince William and the Duchess have scheduled for this week. On Thursday, the royal couple will walk the red carpet at the London premiere of "Mandela: Long Walk to Freedom" in Leicester Square alongside BAFTA-winning director Justin Chadwick and Nelson Mandela's daughter, Zindzi Mandela.

On Friday, Prince William will present medals to Irish Guard soldiers in Aldershot while the Duchess pays a visit to the Shooting Star House Children's Hospice in Hampton, and on Sunday, Prince William will attend the British Military Tournament at Earls Court Exhibition Centre, which raises money for three national Armed Forces charities.

As if that weren't enough, the Duke and Duchess will both attend the screening of David Attenborough's "Natural History Museum Alive 3D" on Thursday, Dec. 11.

Click here to see photos of Kate Middleton wearing what is believed to be the Papyrus Leaf Tiara on loan to the Duchess from the Queen, and click here to see photos of Princess Margaret and the Queen's mother wearing it circa 1930.