(Belgium’s Princess Mathilde and Prince Philippe in New York. Courtesy: Robert Burgess for the Embassy of Belgium, 2011)

In New York, Princess Mathilde of Belgium made a surprise visit to a Central Park Le Pain Quotidien where she sampled teacakes and granola with young Belgian expatriates last Thursday.

In Washington, there would be no teacakes at LPQ.

“They will not have time! Their program is already so full,” said John Cornet d’Elzius, the special adviser to Prince Philippe of Belgium and his wife Princess Mathilde, who are visiting Washington on a three-day economic mission with a delegation of 300 business leaders.

Understandably, their schedule is grueling. Ladies’ power lunches. Charity outreach. CEO summits laced with obligatory photo ops. But on Monday, the royal pair made time for a formal reception at the Belgian Ambassador’s residence to celebrate American and Belgian business partnerships.

Guests, of course, celebrated Belgian pageantry.

“It’s very elaborate,” said D.C. Mayor Vincent Gray, who sat one row behind the royal couple during the small signing ceremony honoring transcontinental Belgian businesses, which preceded the fancy fete. “Definitely one of the more formal events I’ve been to in Washington.”

(Princess Mathilde greets guests at the Belgian Ambassador’s Residence in Washington. Courtesy: Robert Burgess for the Embassy of Belgium, 2011)

Naturally, Princess Mathilde, 38, added to the formality, outshining suit-clad Washingtonians and her Belgian countrymen in a knee-length scarlet cocktail dress adorned with horizontal rows of shimmering beads. She paired the backless sheath with matching satin pumps (dyed to the exact shade of her dress) and understated diamond and pearl teardrop earrings. In true royal form, she wore diamond tennis bracelets on each wrist and a spectacular sapphire and diamond wedding ring (not unlike the one worn by another future queen.)

The princess skipped the tiara.

Six hundred guests overflowed from the Louis XVI-style mansion onto a tented patio overlooking the nine-acre Foxhall estate. Justice Anthony Kennedy, Secretary Kathleen Sebelius, Secretary Ray LaHood and a slew of ambassadors all walked down a mauve carpet through the grand salon lined with 14 harpists from the American Youth Harp Ensemble of Richmond. “One of the harpists is from Belgium, so it was a convenient connection,” said an official.

(Business leaders pose with the royal couple at the residence. Courtesy: Robert Burgess for the Embassy of Belgium, 2011)

The residence was in full bloom, with towering tri-colored arrangements of fresh roses, fashioned by Ambassador Jan Matthysen’s wife Agnes. “I always arrange the flowers for events,” said Matthysen. “The house is so beautiful itself, but I do like adding to it.”

She also decorated the library and dining rooms, where guests sampled spreads of Belgian truffles and fruit-filled petit fours. Beer enthusiasts enjoyed three types of Belgian brews in the estate’s gardens. (It’s rumored Corsendonk pale ale was the popular choice of the evening.)

The royal couple left the party around 9:30 p.m. to prepare for another day of events. Prince Philippe met with Vice President Joe Biden and Senator John Kerry on Tuesday, while Princess Mathilde visited the offices of the playground-building non-profit KaBOOM!, one of Michelle Obama’s favorite charities.

The celebration of what one Belgian official called “the two most important cities in the world!” ended shortly after the royal couple departed.

New York and London would disagree with that claim, but they weren’t on the guest list.