Princesses Beatrice (L) and Eugenie
Britain's Princesses Beatrice (L) and Eugenie arrive for the annual Trooping the Colour ceremony at Horse Guards Parade in central London in Britain June 13, 2015. Trooping the Colour is a ceremony to honour the Queen's official birthday. Reuters/Luke MacGregor

Princesses Beatrice and Eugenie were born into the Royal family and are therefore afforded some privileges that even Kate Middleton and Meghan Markle are not, including being called a princess. But Kate and Meghan may wear tiaras and the Duke of York’s daughters may not, or at least not yet.

The Duchess of Cambridge was first seen wearing a tiara, particularly Queen Elizabeth’s Cartier Halo tiara, when she married Prince William in 2011. It was also her official induction into the Royal family. Since then, she has been seen wearing different tiaras on official royal engagements.

Prince William and Catherine, Duchess of Cambridg
Britain's Prince William and Catherine, Duchess of Cambridge are seen travelling to Buckingham Palace in the 1902 State Landau, along the Procession Route, after their wedding in Westminster Abbey, in central in this London April 29, 2011 file photograph. Reuters/Kieran Doherty/Files

The Duchess of Sussex was seen wearing a diamond bandeau tiara, lent by the Queen as well, only once when she married Prince Harry in May. She hasn’t had the opportunity to attend formal events yet, though.

Meghan Markle in St George's Chapel at Windsor Castle during her wedding to Prince Harry Windsor, Britain, May 19, 2018.
Meghan Markle in St George's Chapel at Windsor Castle during her wedding to Prince Harry Windsor, Britain, May 19, 2018. Owen Humphreys/Pool via Reuters

But Beatrice and Eugenie, who have been princesses all their lives and are directly related to the monarch, have never been seen with a tiara. There’s a simple reason for that: They aren’t married.

Jewellery expert Geoffrey Munn has explained to Town & Country (via the Sun) that because the sisters are both unmarried, they may not wear the ornamental crown.

“Any woman may wear one, but ancient tradition has it that they must be a bride or already married,” he said. “The tiara has its roots in classical antiquity and was seen as an emblem of the loss of innocence to the crowning of love.

“One of the mainstays of European royalty and aristocracy is to do what you have always done, and formal dress, jewellery, and tiaras are just part of this.”

There were exceptions, though. Anne, Princess Royal, was allowed to wear one at age 17 to the state opening of Parliament. The Queen’s sister, Princess Margaret, also wore a tiara on and off throughout her life.

It may take a while before Beatrice can be seen wearing a tiara, but it may be just a few more weeks before Eugenie wears one. Eugenie will be marrying fiancé Jack Brooksbank on Oct. 12 at St George’s Chapel at Windsor Castle, the same venue where Harry and Meghan wed a few months earlier. She is expected to wear a tiara on her big day, and there are speculations that she may honour her mother, Sarah Ferguson, by wearing the one she wore for her wedding to Prince Andrew in 1986.

“She will almost certainly wear a tiara and I think it would be a lovely touch if she opted for the same one her mother wore for her wedding to the Duke of York,” personal stylist Anna Mewes, who isn’t working for the royal family, told Express.

Sarah’s tiara, made by jewellers Garrard, was a gift from the Queen for her wedding.