Once again, Kate was spotted wearing one of Princess Diana's favorite tiaras while at the state banquet tonight at Buckingham Palace.

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William and Kate on the way to Buckingham Palace for the first State Banquet of King Charles’s reign.

The sparkler is quickly becoming Kate's go-to tiara. While tonight she paired the topper with pearl drop earrings her royal order, she has previously worn it with an icy blue Alexander McQueen gown and a plunging blush-colored Marchesa dress, among other ensembles.

One of Diana's most iconic pieces, the diadem obviously holds sentimental value for the newly named Princess of Wales, but it also has an amazing royal history. Sometimes referred to as the Cambridge Lover's Knot, the topper is, in fact, a replica of an earlier tiara.

The piece of jewelry Kate wears was created for Queen Mary in 1914 by the House of Garrard from pearls and diamonds already owned by her family. Mary modeled after her grandmother Princess Augusta of Hesse's headpiece, the original Cambridge Lover's Knot Tiara, which is currently thought to be held in an unknown private collection.

According to the Court Jeweller, when Queen Mary commissioned the piece, she "sacrificed a tiara from her own jewelry collection, the Ladies of England Tiara, to make it."

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Queen Mary wearing the Lover’s Knot Tiara.

After Queen Mary died in 1953, the crown was passed down to her granddaughter, Queen Elizabeth II. The Queen wore the tiara several times in the '50s, before moving on to other pieces like the Girls of Great Britain and Ireland tiara, which have since become her favorites.

In 1981, the Queen reportedly loaned the Lover's Knot Tiara to Princess Diana as a wedding gift. Diana opted instead to wear the Spencer Tiara, a family heirloom, on her big day, but the Lover's Knot became one of her favorite pieces, despite being so heavy that it hurt her head.

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When Diana and Charles divorced, the crown was returned to Queen Elizabeth II—Diana was allowed to keep her jewelry as part of the settlement, but as the tiara was on loan from the Queen, it was given back—and reportedly put into a safe at Buckingham Palace.

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According to People, following Diana's death in 1997, the tiara wasn't seen publicly until 2015, when Kate wore it to much fanfare at a reception at Buckingham Palace.

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Kate in the Lover's Knot tiara in 2016.

She has worn it in total at least nine times.

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Caroline Hallemann
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As the digital director for Town & Country, Caroline Hallemann covers culture, entertainment, and a range of other subjects