Protocol and etiquette aside, when the president of the United States summons an audience, even Washington's most sparkling dinners have to wait.

Last night, some of Washington's glitter class of politicians, diplomats and socialites were somewhat distracted from the opera ball so they could high-tail it out to Andrews Air Force Base to meet the Reagans upon their arrival from their 11-day European sojourn. Tickets for Andrews were not hard to come by.

"I've been here eight years and this has never happened before," said Countess Ulla Wachtmeister, who postponed her pre-ball dinner one hour so that she could get out to Andrews. "They invited the entire staff of the Swedish Embassy too. It's very unique. We could have as many tickets as we want. It's a nice thought."

The Opera Ball is one of Washington's purely social grand events where shimmering silk and glistening emeralds are almost as important as yesterday's political business. But Washington being what it is, politics always interferes. The ball was originally scheduled to take place at the Peruvian Embassy, but due to the war in the Falkland Islands, the Peruvians canceled and the ball was held at the Maylasian Embassy. The crisis in the Mideast also posed a slight problem last night. Saudi Ambassador Faisal Alhegelan was not able to host his own dinner, having been called back to Saudi Arabia for a conference.

At $250 a ticket, the opera ball is the largest single fund-raiser the Washington Opera holds annually. The tickets are among the more expensive and coveted tickets in town. About $100,000 was reportedly raised last night.

About 500 people gathered at the Malaysian Embassy around 10 p.m. to waltz and boogie, following traditional dinners at 23 other embassies around town. As with most Washington parties, the fancier the guest list, the more prestigious the party.

Starting the evening with dinner at the Swedish Embassy was therefore a plum this year since the guest list of 22 included Attorney General William French Smith and his wife, Jean Smith, the ball chairman, Walter and Leonore Annenberg, and the Holmes Tuttles, close friends of the Reagans.

Dinner of roast duck was served at the Swedish Embassy in the dimly lit dining room bedecked with scarlet roses. It was an evening of many toasts.

Ambassador Count Wilhelm Wachtmeister toasted the Reagans upon return from their trip. The attorney general then toasted the king and queen of England. Wachtmeister then toasted former chief of protocol Leonore Annenberg, saying, "You are missed every day. You were greatly loved when you were here." At which point Annenberg said, "Oh, I think I'm going to start crying." After everyone sat down, Walter Annenberg proposed a toast to the Wachtmeisters in celebration of their 35th wedding anniversary. Ulla Wachtmeister then toasted her husband as "the most wonderful husband in the world." Leonore Annenberg toasted them as "the most ambassadorial couple in Washington." And when everyone had just about settled down with some Swedish caviar, Jean Smith toasted "the superb cuisine. Finally everyone got down to some serious caviar, duck, ice cream eating and champagne drinking.

"I want us to toast each other," said Walter Annenberg at the end of the meal, "in hope that we continue to deserve each other."