The Carnegie Hall stage was empty except for the traditional black concert grand.

A parade of world renowned pianists, 24 in all, took turns at the keyboard, thrilling the black-tie-and-tails audience.But at the end of the evening, the true star took its place on stage: a rare East Indian ebony and dyed Swiss pear piano valued at a half million dollars.

It was the 500,000th piano produced by New York's own Steinway and Sons. A concert grand, it was made by Wendell Castle, a furniture designer and craftsman from Rochester, N.Y.

Though the hall was filled with virtuosos, Steinway sought to symbolize the future of music by choosing Albert Kim, a 9-year-old student at the Manhattan School of Music, to play the piano in public for the first time.

The 100,000th Steinway, built in 1903, is in the permanent collection of the Smithsonian Institution. Number 300,000, presented to President Franklin Roosevelt in 1938, is in the East Room of the White House.

All evening at the June gala to celebrate Steinways, the music of Liszt, Chopin, Ravel and Paderewski filled the concert hall.

Among the virtuosos who played was the Russian-born Shura Cherkassky, who made his concert debut in 1923. He brought the audience to its feet with Josef Hofmann's "Kaleidoscope."

Lazar Berman, a Muscovite who made his U.S. debut in 1976, was cheered for his selections by Rachmaninoff and Prokofiev.

In a stunning finale, 19 of the pianists, including Navah Perlman, teenage daughter of violinist Itzak Perlman, Ruth Laredo, Jose Feghali and Alexis Weissenberg played Shumann's "Carnival."

The musicians silently entered and left the stage, allowing each segment of the composition to flow effortlessly into the next.

The audience, however, was disappointed that Van Cliburn, the Texan who became a national hero after winning the 1958 Tchaikovsky Competition in Moscow, did not inaugurate the Steinway as had been rumored.

Cliburn, who has not recorded or given a major concert since 1978, said in a recent interview that he planned to play Carnegie Hall "eventually."

He teased fans expecting a major comeback by playing for the Reagans and Gorbechevs at the White House during the December 1987 summit and at the opening of the Bob Hope Cultural Center in Palm Desert, Calif., a month later.

Accepting the Steinway Foundation's award for his inspiration to young pianists, Cliburn only thanked his mother, Lillian: "She introduced me to the glory and power of the Steinway piano at a tender age. She is undeniably my artistic inspiration." His mother was in the audience.

"We lean heavily on the parents to help translate ideas and ideals into reality," said the musician, who sponsors the Van Cliburn International Piano Competition, to be held in 1989 in his home city of San Antonio.

Ignoring shouts from the audience to play the 500,000th Steinway, Cliburn left the crowd wondering when, if ever, he would again play Carnegie Hall.

Concert pianists have long favored the clear, bold and rich tones and the quick action of the keys in the instruments made by the 135-year-old company.

A fixture in many of the world's great concert halls, Steinways can produce great changes in volume without losing tone quality.

Steinway says its factories in Long Island City, N.Y., and Hamburg, Germany, create only 3,500 pianos each year, compared with other manufacturers who produce up to 200,000 annually.

The Carnegie Hall gala also helped raise funds for the Steinway Foundation, which promotes the composition and performance of piano music.

It is estimated that more than 20 million Americans play the piano and more than 155,000 are purchased annually here.

The 500,000th Steinway will go on a world tour, though long-term plans for it are not yet known.

According to Bruce Stevens, president of Steinway and Sons, "We have stipulated that its final destination be one where it can be shared by music lovers from around the world."