You didn't need a program to tell it was a gala. The opening of the New York City Ballet's 10-day Tchaikovsky Festival in the New York State Theater at Lincoln Center Thursday night wore its sense of occasion like a diamond tiara. A veritable legion of the famous showed up to certify the evening's social standing, including New York's Gov. Hugh Carey, Sen. Charles Percy (R-Ill.), Jacqueline Onassis, Lee Radziwill, Oscar de la Renta, William F. Buckley, Joanne Woodward, Louis Malle and Kurt Vonnegut, not to mention such dance notables as Natalia Makarova, Arthur Mitchell, Edward Villella and Alexandra Danilova.

After the performance, in a grand foyer converted into a garden court with potted trees and floral garlands, celebrities and sponsors sipped vodka and wine in black-tie splendor while being served duck liver mousses and filet Stroganov. If you were within range of the bandstand, you could glimpse such couples as Gloria Vanderbilt and designer Rouben Ter-Arutunian twirling around the ad-hoc dance floor.

The glitter extended onto the stage. A half-million dollars worth of innovative decor commissioned from Philip Johnson, architect of the New York State Theater, and his partner John Burgee framed the evening's ballets. Choreographer George Balanchine had asked for an "ice palace" conducive to Tchaikovskian grandeur, and what they've given him is a forest of clear, tubular, plastic modules (six miles and 41,000 pounds of them) that can be assembled into a variety of brillantly reflective scenic structures.

The Tchaikovsky Festival, which will introduce 13 new ballets by Balanchine and five other NYC Ballet choreographers, augments a company custom that began with the historic Stravinsky Festival in 1972, and continued with the Ravel Festival of 1975. There's more than sufficient esthetic rationale for the current tribute. As a composer for the ballet, Tchaikovsky not only restored respectability to a once-scorned musical endeavor, but also enriched the repertoire with what remain its greatest masterpieces. Dance forms and dance impetus, moreover, abound in the music he composed in all other genres. Balanchine's reverence for Tchaikovsky dates from his childhood, and the NYC Ballet has engendered 15 Tchaikovsky ballets since its founding, 10 of which are to be staged during the festival along with the new works.

Yet, however natural and fitting the present festivity may be on theoretical grounds, Thursday night's inaugural had the feeling of a celebration by rote. Galas are by now both a cliche and an industry unto themselves -- the chic, the fanfare and all the conspicuous consumption have become too formulaic to have much spontaneous lift to them any more. And the evening's program, despite a decent share of artistic merits, seemed rather a contrived grab bag of material, heaped together more for effect than content.

Preceding the dancing were introductory remarks by NYC Ballet Orchestra conductor Robert Irving, and a musical prologue consisting of the "Romeo and Juliet" Overture and vocal selections from the operas (including a duet from "Undine" later incorported into the score for "Swan Lake"). Of the evening's three ballet premieres, not surprisingly it was Balanchine's "Mozartiana" that seemed closest to major accomplishment. The choreography is new, but not precisely brand new -- Balanchine had done a previous treatment of the score in 1933, and according to those familiar with the earlier version, the new opus corresponds in a number of particulars.

In any case, the present "Mozartiana," set to Tchaikovsky's identically titled Orchestral Suite Number Four, is a comely work in a more or less conventional neoclassic vein, not altogether consistent in inspiration but plentiful in felicity nonetheless. The high points are the opening, sweetly reverential "Preghiera" movement for ballerina Suzanne Farrell and a quartet of petite young students from the School of American Ballet -- a study in the eloquence of simplicity -- and a sparkling set of variations for Farrell and Ib Andersen that constitute the fourth movement. In between a bouncy "Gigue," smartly danced Thursday by Christopher d'Amboise replacing injured Victor Castelli, and a "Menuet" for four women. An assertive "Finale" involves the entire cast in a typically Balanchinian culmination. Ter-Arutunian's costumes, which have the women in short, flared black dresses with white trim, giving them the look of French chambermaids, struck an anomalous note, but Philip Johnson's tubular set, shaped by Ronald Bates into grand archways, made its best effect of the evening here.

Peter Martins' "Capriccio Italien," danced by School of American Ballet students with impressively self-possessed Lisa Jackson at their head, alludes to both of the choreographer's chief artistic models -- Balanchine, in a neoclassic ensemble of seven tutu-clad couples, and the Danish master, August Bournonville, in a mock-Neopolitan group of three virtuosic males and six dirndl-clad women. Jerome Robbins' contribution was a borderline sugary duet to the amorous slow movement of the First Piano Concerto, intriguing in its ice-skating imagery, and most fetchingly performed by Darci Kistler and Ib Andersen. A shaky account of the finale from Balanchine's "Diamonds" brought the program to a close. All three premieres will bear further watching, however.

Still to come are 10 new creations by Balachine, Robbins, Martins, John Taras, Jacques d'Amboise and Joseph Duell before the festival winds up on June 14, and from among these, if luck holds, an ample fallout for the company's permanent repertoire.