Kate Middleton was the picture of elegance at the  600th anniversary event for her and Prince Williams‘ alma mater, St. Andrews, at the Metropolitan Museum of Art Tuesday evening.

Kate Middleton’s St. Andrew’s Party Look

Middleton attended the fundraising fete in a midnight blue Jenny Packham gown with emerald and diamond earrings, and wore her hair swept up into a loose bun. At her side, Prince William’s black tie attire featured a black tuxedo with matching bowtie.

Middleton has worn the glamorous Jenny Packham gown twice before – at the 100 Women in Hedge Funds dinner in October 2013, and at the National Portrait Gallery function in February of this year.

Among the guests at the event – for which plates went for $10,000 a piece – were Anna Wintour, Olivier Sarkozy and Mary-Kate Olsen, and Seth Meyers.

In addition to those who turned up for the dinner were roughly 200 fans of the Duke and Duchess of Cambridge who’d camped out on the opposite side of the street as the museum. As one of the women in the crowd Sahina Katz explained, Middleton’s popularity is due in part to how relatable she seems.

“I think [her popularity is related to] the idea that she could be any one of us,” Katz told Vanity Fair. “Also, I think, there’s quite a throwback to the Princess Diana days in terms of her personability and in how she and Will really engage with the public.”

“I get the impression she’s more than just a pretty face, in terms of her background in academia,” Katz added. “There’s that element that you can have a bit more of an in-depth conversation with her than with other celebrities.”

Prior to the St. Andrew’s dinner, William and Kate had a number of other engagements in the Big Apple, including the Brooklyn Nets and Cleveland Cavaliers basketball game, a luncheon with Hillary Clinton and a visit to the 9/11 Memorial. William also took a couple of hours out of his trip to head down to Washington, D.C. to chat with President Barack Obama.