Kate Middleton wears pearl necklace also worn by Princess Diana and Queen Elizabeth

Monday marked Queen Elizabeth and Prince Philip’s 70th wedding anniversary, so to mark the historic occasion the entire royal family celebrated together at Windsor Castle in Berkshire.

The Duke and Duchess of Cambridge, Prince Harry, and Charles and Camilla were all spotted making their way into the royal residence, in the countryside, to commemorate the couple’s enduring marriage.

Kate, William, and Harry all made an appearance at the Queen’s platinum wedding anniversary celebration. (Photo: Getty Images)

Princes William and Harry opted for smart black tuxedos, while a pregnant Kate Middleton appeared to be wearing a lace black dress.

The Duchess of Cambridge borrowed a stand-out pearl choker from the monarch. (Photo: Getty Images)

Although the duchess’s outfit couldn’t be seen in all its glory from the few photos that were taken, it’s believed she was wearing a frock by Diane Von Furstenberg, one that she’s stepped out in on multiple occasions.

The $1,038 floor-length style was worn by Kate earlier this month at The Anna Freud Gala Dinner. The 35-year-old royal also wore the dress for the 2014 Royal Variety Performance, when she was pregnant with Prince George.

However, it’s the duchess’s jewels that really stood out. Middleton, who’s expecting her third child in April, borrowed one of the Queen’s most striking necklaces: the Four Row Japanese Pearl Choker.

The piece is thought to have been made in the 1970s by royal jeweler Garrard from pearls given to the Queen by the Japanese government. It was first seen on the monarch in 1982 and features four rows of pearls with a central diamond clasp.

It’s the first time Kate has worn the pearl piece. Princess Diana was also a fan of the choker, having been spotted wearing it to a banquet at Hampton Court Palace in 1982.

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