Why Meghan Markle and Kate Middleton can wear tiaras, but Eugenie and Beatrice can't

When Meghan Markle and Kate Middleton married into the royal family, both accessorized their wedding dresses with diamond tiaras, and the Duchess of Cambridge sometimes dons similar sparkling headpieces for special occasions.

So why do Princesses Beatrice and Eugenie, Queen Elizabeth’s own granddaughters, have to make do with mere fascinators?

According to royal tradition, tiaras are typically reserved for married women, People reports, meaning that even members of the family with “princess” or “duchess” in their titles aren’t guaranteed the right to wear one.

Even after tying the knot, royal women rarely reach for tiaras. So far, Meghan, the Duchess of Sussex, has only worn one: the Queen Mary Diamond Bandeau for her May wedding to Prince Harry. And after wearing the Queen’s Cartier Halo tiara to marry Prince William in 2011, Middleton has only sported the accessory five other times, and only for major white-tie events.

There are exceptions to the rule: The Queen’s daughter Princess Anne, for instance, wore a tiara to the state opening of Parliament when she was still a teenager.

Still, it’s likely that Princess Eugenie’s first time wearing a diamond topper will be on October 12, when she marries Jack Brooksbank.

This story originally appeared in the New York Post.