In 1963 Pope Paul VI made a dramatic break with tradition when he celebrated his coronation mass outdoors in St. Peter's Square. Last Sunday, Pope John Paul I followed Pope Paul's lead toward demystifying the papacy by declining to be crowned with the papal tiara, a 10-pound crown of gold and silver that traditionally has been part of the papal enthronement ceremony.

Assuming that future popes follow the trend toward removing the regal trappings from the papacy, the tiara may become for future generations one of the more obvious symbols of papal days gone by.

In fact, the tiara worn by Pope Paul is on permanent display at the National Shrine of the Immaculate Conception here in Washington and has been drawing large numbers of tourists this summer. According to Bill Grillo, assistant director of the shrine, the number of visitors to view the display this year has increased two-thirds over the normal summer flow.

"Apparently," Grillo said, "tourists are finding out while they are in Washington that the tiara is here and they are stopping by to see it."

The tiara's journey to the shrine's crypt gallery, where it sits on a pedestal enclosed in a glass case, began in 1964 when Pope Paul laid his coronation crown on the altar of St. Peter's and announced that he was giving it to the poor of the world. Francis Cardinal Spellman of New York later announced the tiara, set with diamonds, emeralds, rubies and aquamarines and estimated at the time to be worth $17,500, would be sent to the United States by the Vatican in recognition of American generosity to the hungry and dispossessed people of the world.

Im 1968 after touring the United States, the crown was presented by Archbishop Luigi Raimondi, apostolic delegate to the United States, to Msgr. William McDonough, the shrine's director.

The tiara, now estimated by Grillo to be worth $35,000, is protected by a motion alarm system. Enclosed in the glass case with the tiara is a stole worn by Pope John XXII at the opening of the Second Vatican Council and a commemorative coin marking Pope Paul's address to the U.N. in 1966.

In keeping with the concern Pope Paul expressed for the poor by giving away the tiara, an offering box has been placed next to the display. Contributions are sent to Mother Teresa of Calcutta, an Indian nun who ministers to the poor. Visitors contributed more than $30,000 last year, Grillo said.

When Mother Teresa visited the shrine in 1975, many thought she would be repulsed by its grandeur. But, Grillo said, she thought the shrine a worthwhile structure and was pleased people would have the opportunity to view the tiara and contribute to her efforts as well.

The display is open to visitors seven days a week, 7 a.m. to 7 p.m.