There’s One Princess Diana Fashion Go-To That Kate Middleton Won’t Copy

Princess Kate is a rule-following royal.

Kate Middleton loves to sartorially honor her late mother-in-law Princess Diana, between her royal jewelry hand-me-downs (which includes her sapphire engagement ring that once belonged to Lady Di) to recreating some of her most iconic looks. However, there is one Diana fashion go-to that Kate refuses to copy: wearing all black.

An old royal style rule that predates Diana prohibits royals from wearing all black, unless they are in mourning or attending a funeral. However, Diana had been known to wear black on occasions that have nothing to do with death—after all, one of her most legendary looks was an LBD.

According to designer Dame Zandra Rhodes, who created pieces for the princess, Diana was drawn to black. When she first became a royal, she would have the black pieces made in different colors, however.

“She was very shy. She would come into my shop in Mayfair and go through the rails,” Rhodes told Saga magazine, per Hello!. “Sometimes, she picked something in black, which the royals weren’t allowed to wear except at funerals, so we would make it in her size in a different colour.”

Eventually, Diana began ignoring the rule and made black one of her go-to colors. In 1981, the late Princess of Wales wore a black gown, designed by David and Elizabeth Emanuel (who designed her wedding dress), to a fundraising event, and her fiancé at the time, Prince Charles, was not too happy about it.

“Only people in mourning wear black!” Diana recalled him saying when being interviewed for her biography 10 years later. The princess would go on to wear many newsworthy black looks, her most famous being the black off-the-shoulder “revenge dress” that she wore the night that Prince Charles admitted to committing adultery with Camilla Parker Bowles (now Queen Camilla).

Kate, on the other hand, appears to be a rule follower, and does not often stray from the style regulations put in place for royals. This rule, in particular, is one that Middleton appears to follow, as she usually wears a color or a neutral, unless she is mourning a loss.