Kate Middleton’s engagement ring used to belong to Prince Harry and not Prince William.

The Duke of Cambridge used Princess Diana’s sapphire and diamond engagement ring when he proposed to Middleton. However, the item originally belonged to Prince Harry.

“After Diana died, the boys both chose a keepsake from Kensington Palace when they moved to Charles’ rooms in St James’s Palace,” a source said.

“William picked his mum’s Cartier watch, and Harry picked her sapphire and diamond engagement ring. But they had an agreement that whoever got engaged first would have Diana’s ring – and of course that was William and Kate.”

Meanwhile, Princess Diana’s former butler Paul Burrell had another version based on what he shared in the Amazon Prime Documentary “The Diana Story.” According to him, Prince Harry offered the ring to Prince William when he was about to propose to Middleton.

“Harry said to him: ‘Wouldn’t it be fitting if she had mummy’s ring?’” Burrell said.

“Then one day that ring will be sat on the throne of England. Harry gave up his precious treasure. His one thing he kept from his mother, he gave to his brother. That’s selfless, kind, and exactly who Diana was.”

Prince William and Middleton dated for almost a decade before the future king proposed to her. The second-in-line to the throne admitted that he had been carrying the engagement ring for weeks before he popped the big question as he was waiting for the best time.

When he finally gave the ring to Middleton, he warned the duchess to keep it safe or she would be in “big trouble.”

Middleton said that she hoped she could look after the sentimental band because it is “very, very special.” Prince William quipped, “If she loses it, she’s in big trouble.”

In related news, netizens felt that Prince Harry’s wife, Meghan Markle, tricked and betrayed Middleton. Markle reportedly wanted them to appear friendly at Wimbledon. However, she threw shade at the Duchess of Cambridge by turning down the Vogue cover because it was “boastful” when Middleton graced the magazine cover three years ago.

Prince William, Kate Middleton and Prince Harry Prince William, Kate Middleton and Prince Harry during 'The Patron's Lunch' celebrations for The Queen's 90th birthday at The Mall on June 12, 2016 in London. Photo: Getty Images/Jeff Spicer