Kate Middleton's $35 Zara Necklace is (Unsurprisingly) Sold Out

Getty ImagesAnother day, another company strikes gold, thanks to Kate Middleton. One day after the Duchess of Cambridge wore a $35 sparkly, crystal-bead Zara necklace to attend the premiere of "Mandela: Long Walk to Freedom" to honor the late Nelson Mandela, the necklace has sold out on Zara's website.

Middleton paired the piece with a cream-colored Roland Mouret gown and wore her hair in a casual ponytail — a departure from the previous evening, when she showed off a glittery tiara (a family heirloom valued at quite a bit more than $35) for an event at Buckingham Palace.

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It's no surprise that shoppers swooped in to buy out the necklace — Middleton's ability to excite and influence the fashion masses is a phenomenon dubbed the "Kate Effect." When the duchess posed for her engagement photo with Prince William in 2010, she wore a blue Issa London wrap dress, which sold out in 24 hours. In order to keep up with the demand (still going strong more than two years later), the company teamed up with Banana Republic to create a $130 knockoff. Meanwhile, Middleton's blue sapphire-and-diamond engagement ring inspired an entire industry of replicas (you can buy your own for $30), and this past May, after she hit the town carrying a series of mini-clutch bags, famed handbag designer Lulu Guinness went to work on a new line of pint-sized purses, saying, "If she's done anything for the handbag, it's the fact that she wears small clutch bags. Personally, I am making my clutch bags smaller next season, so they're more delicate and ladylike, and that's to do with her, I think." And the $75 Jolene knotted-front fuchsia dress that Middleton wore in August for her first family photo after giving birth to Prince George a month earlier, sold out just 48 hours after the photo was released.

The girl even made nude pantyhose cool. Well, popular, at least. Hey, even royals make mistakes.

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