Princess Beatrice, Princess Eugenie
Pictured: Princesses Beatrice, Eugenie attend Royal Ascot Day 1 at Ascot Racecourse on June 19, 2018 in Ascot, United Kingdom. Getty Images/Chris Jackson

Princess Beatrice and Princess Eugenie have not been spotted wearing a tiara like Kate Middleton and Meghan Markle because they are both not married yet.

Geoffrey Munn, a jewelry expert, told Cosmopolitan that only married royals are allowed to wear the headpiece. Markle, for instance, was spotted wearing a tiara for the first time on the day of her wedding to Prince Harry. The Duchess of Sussex's wedding tiara was originally owned by Queen Mary, and it featured diamond center-stone adorned with filigree.

“Any woman may wear one, but ancient tradition has it that they must be a bride or already married. 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, jewelry, and tiaras are just a part of this,” Munn said.

In related news, since Princess Eugenie will soon tie the knot with Jack Brooksbank, royal fans may finally see her wearing a tiara. There are speculations suggesting that she will wear her mom Sarah Ferguson’s hair accessory.

Rachel Russell, a journalist for Express, said that Princess Eugenie might wear the tiara that was given to her mom by Queen Elizabeth II and Prince Philip. It was commissioned from Mayfair jewelers Garrard & Co, and it came with matching bracelet, earrings, and necklace.

However, it is also possible for Princess Eugenie to wear an entirely different tiara on her wedding day. After all, the 28-year-old princess is known for breaking protocol. She may still pay tribute to her mom and dad, Prince Andrew, by wearing a dress that is similar to what Ferguson wore during her wedding in the 1980s.

Ferguson’s long-sleeved bridal gown featured secret love symbols that represented her and Prince Andrew’s relationship. However, the couple divorced years after their wedding. Multiple reports claimed that Prince Andrew and Ferguson are still residing in the Royal Lodge together even though they are legally separated. Ferguson also previously confirmed that she and Prince Andrew are still best friends.