When Kate Middleton arrives at an event adorned in her royal jewels [1], you know the evening's bound to be a fancy one. But when the duchess is showing off a tiara, well, her look will be one for the books.

While Kate hasn't worn a tiara since the Chinese state dinner [2], the annual diplomatic reception at Buckingham Palace called for a stunner. The Cambridge Lover's Knot piece was favored by Princess Diana [3] and was lent to Kate by Queen Elizabeth II. It's definitely the perfect complement to Kate's lacy Alexander McQueen gown and chandelier earrings.

Read on to get a glimpse of the duchess [4]'s arrival, and take in her fourth-ever tiara moment. Plus, see a flashback of Princess Diana in the same exact head piece back in 1983!

Princess Diana wearing the Cambridge Lover's Knot Tiara in 1983

Kate Middleton Wearing the Tiara For the Diplomatic Reception in 2015