Kate Middleton, Princess Diana
Photo: Getty

The world hasn’t seen Kate Middleton in formal wear in a while, mostly because the Duchess of Cambridge had been on maternity leave since the April birth of her third child, Prince Louis. The Duchess came back from her maternity leave earlier this month, and she’s back to attending engagements and events, like tonight’s state banquet.

The banquet is being held in honor of King Willem-Alexander and Queen Maxima of the Netherlands, and Kate looked lovely at the event. She wore a blue dress, which she paired with what looks like Princess Diana’s teardrop pearl earrings, and a matching diamond-and-pearl necklace that once belonged to the Queen Mother. Kate topped off the look with the Lover’s Knot tiara, which matched perfectly with the rest of her jewelry, as it also features diamond and pearls.

Related article: 20 Of The Most Amazing Hats At Princess Eugenie’s Royal Wedding 

The tiara was a favorite of Princess Diana’s, and she wore it on several occasions, including, famously, with a white sequined dress and high-collared jacket that many dubbed the “Elvis outfit.”

Kate Middleton, Princess Diana
Princess Diana wearing the tiara in Hong Kong in 1989. Photo: Getty

The tiara has a long history, and according to Town & Country, it’s actually modeled after another tiara called the Cambridge Lover’s Knot Tiara, which was owned by Queen Mary’s grandmother Princess Augusta of Hesse. The current tiara was made in 1914 for Queen Mary, before being passed down to her granddaughter, Queen Elizabeth II. The Queen loaned it to Diana on several occasions, but she wasn’t allowed to permanently keep it after her divorce from Prince Charles.

Related article: All About Princess Diana’s Second Wedding Dress

Kate Middleton, Princess Diana
Princess Diana wearing the Lover’s Knot tiara in Italy in 1985. Photo: Getty

Diana wore the tiara last in 1991, and it wasn’t seen again until Kate wore it to the annual Diplomatic Reception at Buckingham Palace in 2015.

Kate Middleton, Princess Diana
Kate Middleton in the Lover’s Knot tiara in 2017. Photo: Getty/Max Mumby/Indigo

Kate wore it again to the Diplomatic Reception in 2016, and also to a state banquet when King Felipe and Queen Letizia of Spain visited the United Kingdom in 2017.

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This article originally appeared on Harper’s Bazaar US.