Diane Von Furstenberg thinks it is "fun" to see Duchess Catherine in her dresses.
The British royal - who was known as Kate Middleton before her marriage to Prince William - wore the designer's green silk Maja dress for the first time at a reception welcoming her and her spouse to America in 2011, and Diane is pleased she is a fan of her work.
She said: "It was so fun to see the duchess wearing my dress. I remember she came off the plane wearing it - she's worn it several times since - such a wonderful compliment. I think she's great."
Another big fan of the designer is US First Lady Michelle Obama - who wore one of her famous wrap dresses for her family's official Christmas card portrait in 2009 - and Diane insisted on receiving a memento of her wearing the gown.
She told Britain's Grazia: "I have always believed the best kind of celebrity association is when you don't plan it.
"With the First Lady, I had no idea she was going to wear my dress.
"It was only that Annie Leibovitz told me she'd shot Mrs. Obama in DvF for Vanity Fair. So she sent me the photograph then after that they chose the picture to become their Christmas card.
"So I called the White House and made them send me a card."