Since then, Middleton—whose styles are often snatched up by idolizing British and American consumers alike—has also been photographed wearing various versions of the headpiece.
"I was doing fascinators before the royal wedding, but now everybody knows what that word is," Pfanenstiel said. "Kate Middleton has definitely brought that style to the norm."
The trend has also carried over to New York City shop Suzanne Couture Millinery. Suzanne Newman, who has been crafting hats for the Kentucky Derby for 28 years, said her store has seen a budding interest in what she called a hatinator—a midsize hybrid between the smaller fascinator and the traditional brimmed hat.
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After the royal wedding, Newman said her business doubled, and she now makes several hundred each year. That includes the 60 hats she had created for this year's Derby as of Saturday night.
Newman makes only custom hats, which typically range from $400 to $2,000. The most expensive hat she ever created, sold at the top of that range, was a brim hat with deeply dyed fuchsia, orange and red vulture feathers, each of which took a few hours to soak up the color.
"It was a very stunningly beautiful hat," she said, "but it was very time-consuming."
Adding to the bill is the Kentucky Oaks, The Derby's lesser-known sister race that is held the day before the main event. Many of Newman's clients have hats made for both The Derby and the Oaks, the latter of which encourages guests to wear pink in support of breast cancer awareness.