Kate Middleton Stuns in Royal Family's Heirloom Tiara

Viscountess Linley, left. The Duchess of Cambridge, right. It seems as if Kate Middleton might have a thing for the late Princess Margaret.  Queen Elizabeth's younger sister — a bit of a glamorous wild child back in the day — was the previous occupant of Kensington Palace's apartment 1A, the same residence that the Duke and Duchess of Cambridge so famously moved into this year. And last night, Kate set hearts aflutter by finally acting like a princess and walking out the front door with a dazzling diamond tiara secured atop her famous head of hair — the same one that Princess Margaret so loved.

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Named the "Papyrus tiara" as well as the "Lotus tiara," it was created in 1923 by Queen Elizabeth II's mother, also named Elizabeth (but known in popular culture simply as the Queen Mum) who had a sharp personal style and was played to sparky perfection by Helena Bonham Carter in "The Kings Speech."

The Queen Mother, left. Princess Margaret, right. The tiara, originally a diamond and pearl necklace given by her future husband, King George as a wedding present, was transformed after the Queen Mum flexed her new royal muscle six months after their union and sent the Greek-style bauble off to royal jeweler Garrard to be refashioned into something she liked better: a looping, Art-Nouveau-inspired tiara that to this day is perhaps the chicest one in the vault. She wore it like a flapper, low and across her forehead, as well as like a princess, perched regally on her head, much as Kate did last night.

The Papyrus Tiara, top. The original necklace, bottom.In 1959, the Queen Mum then passed on the tiara to Princess Margaret, who was often in the gossip columns for her nightclub antics and many suitors. Nevertheless, the tiara's feminine sparkle made it one of Margaret's absolute favorites: She regularly wore it until her death, and even lent the precious crown to her future daughter-in-law, Serena Armstrong-Jones, for the 1993 wedding to her son, Viscount Linley.

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Since then, however, the tiara has stayed out of the press — that is, until last night, when it was snapped sitting atop the head of current royal fashion plate as she sped off to a fancy diplomatic reception hosted by the Queen. Considering that the Duchess of Cambridge has one of the world's greatest collections of jewelry at her disposal, it's kind of exciting to see that she finally took advantage of the fact and donned a diamond-laden tiara. As the future Queen of England she literally is one of the only people on earth who can legitimately do so. Well done, Kate.

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