What's in a name? In the case of George Balanchine's evening-length ballet called "Jewels," performed by the New York City Ballet for the first time this season at Kennedy Center last night, both nothing and everything.

It is presumably true that the idea for the work originated in a visit Balanchine paid to the Van Cleef and Arpels showrooms in 1966, and it is certainly the case that the jewel motif is carried forward in the three movements -- "Emeralds," "Rubies" and "Diamonds" -- and in Peter Harvey's scenery and Karinska's costumes. But it was Balanchine himself who once told us that "the ballet has nothing to do with jewels."

What he undoubtedly meant was that this isn't a ballet "about" precious stones, which is pretty clearly the case anyway. More apropos are the "national" associations invoked by the musical and choreographic idioms of the trilogy -- the leafy, aquatic tendresse of the "French" opener, to the music of Faure; the urban American speed, action, wit and irreverence of "Rubies," with its jazzy Stravinsky score, and the classic splendor of the Russian imperium in "Diamonds," set to Tchaikovsky's Third Symphony (minus its first movement). And yet, "Jewels" also has a radiance and decorative glamor that are unusual in the NYCB repertoire, and choreographically speaking, it is a collection of gems.

As "Jewels" performances go, last night's was an erratic succession of ups and downs. "Emeralds" seemed sluggish, not just in tempo but in impulse.Merrill Ashley, with her tidy manner and impeccable technique, has never had the roundness or resonance for Violette Verdy's old role; Gerard Ebitz, her partner, was closer to the mark. The movement had its high point in the Elysian stroll of Sean Lavery and Karin von Aroldingen -- the latter can suggest the pathos of a Garbo in the slope of a shoulder or lift of the chin. "Rubies" went well -- Wilhelmina Frankfurt was all sasssy angularity, and Patricia McBride and Robert Weiss chased each other with the proper mixture of fun and deviltry. After a rather tepid adagio, Suzanne Farrel, Peter Martins and the ensemble closed "Diamonds" in a breathtaking accumulation of grandeur.