With Prince William second in the line of succession, Kate Middleton is often referred to as the future queen. And for the recent public event, she looked nothing less than a regal queen in her Lover's Knot tiara studded with dazzling diamonds.

On Wednesday evening, the Duchess of Cambridge arrived with her husband Prince William for the Queen's Diplomatic Corps reception at Buckingham Palace and joined Queen Elizabeth II, Prince of Wales and the Duchess of Cornwall in welcoming the dignitaries and other guests. According to Hello, Kate chose an uber-classy navy-blue gown by Alexander McQueen and she teamed it up with gorgeous diamond jewellery including a tiara.

As per the reports, royal fans and followers "went crazy" over the tiara and queenly look. She wore her hair in a neat bun that showed off her exquisite diamond necklace and earrings.

It is said that the tiara previously belonged to Princess Diana. She had received it from the queen as a wedding gift in 1981. The adornment was originally crafted for Queen Mary in 1914 by the House of Garrand. It is intricately designed with diamonds and pearls that belonged to her family.

This is not the first time Kate adorned the headpiece. She was seen wearing it in 2015's Diplomatic Corps reception. She also wore her Royal Family Order brooch, an honour she received from the queen this year. She was presented with it for her dedication and services to the sovereign. As for Prince William, he looked dapper in his classic black suit.

Diplomatic Corps reception is an annual event that is organised lavishly every year at the Buckingham Palace in honour of the members of Diplomatic Corps, ambassadors, high commissioners, and government officials. About 1000 guests are invited including senior members of the royal family. The event takes place every December, ahead of Christmas. As per Hello, the event follows "strict 'white tie and decorations' dress code." This requires men to be dressed in tailcoats and women to be wearing full-length gowns. Tiaras, medal, and Royal Orders are also displayed during this event.

kate middleton
Kate Middleton at the Baftas Getty

As for the 93-year-old monarch, she was dressed in a pristine white gown by Angela Kelly and paired it up with her emerald and diamond crown and jewellery.