The Princess Royal and her nieces, Princess Beatrice and Princess Eugenie are royals by birth
It's always exciting when members of the royal family step out wearing tiaras, but the occasions are very rare.
Typically, the likes of the Queen Consort Camilla and the Princess of Wales wear them for state banquets or the annual Diplomatic Corps reception at Buckingham Palace. Take a look back at some of the most incredible tiara moments through the years in the video below.
WATCH: Stunning royal wedding tiaras through the years
It's rare to see the royals wear a tiara before their wedding day, including Princess Beatrice and Princess Eugenie, who are also royals by birth. But the Princess Royal was afforded the rare privilege before her first marriage to Captain Mark Phillips in 1973.
Princess Anne, 72, first wore a tiara at the age of 17 in an official portrait but she also frequently wore sparkling headpieces for evening events such as film premieres, charity dinners and balls.
Princess Anne wearing the Meander tiara in Austria in 1969
This is likely because the occasions at the time called for a white tie dress code, where men wear an evening tailcoat and women wear floor-length evening gowns, white gloves and a tiara.
In 1969, Anne wore the Cartier Halo tiara for a night at the cinema with Princess Alice, Countess of Athlone. The diamond headpiece, made up of a band of scrolls, was famously worn by Kate Middleton on her wedding day to Prince William in 2011.
Anne wearing the Cartier Halo tiara in 1969
The Princess Royal was also regularly pictured in the Meander tiara which once belonged to Princess Andrew of Greece and Denmark. Anne's daughter, Zara Phillips, borrowed the jewels for her wedding day to Mike Tindall in 2011.
Anne wasn't the only British-born Princess to wear a tiara before marriage – the Queen's sister, Princess Margaret, also wore headpieces before her wedding to Antony Armstrong-Jones in 1960. Her favourites included the Lotus Flower and the Cartier Halo tiaras, both worn by the Princess of Wales.
While there is a possibility that we may see William and Kate's daughter, Princess Charlotte, wear a tiara before her wedding day, if she attends a state banquet, the royals no longer tend to wear jewels for film premieres or evening charity dinners.
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