Certain works have become milestones in the ballet repertorya test of maturity for the company doing them. Previously the 19th-century classics like Swan Lake and Sleeping Beauty served this function, but George Balanchines 1967 neo-classic Jewels (through Feb. 7) is shaping up to be their contemporary equivalent. Its trio of ballets very loosely inspired by precious gems (thus Emeralds, Rubies, and Diamonds), with a multitude of showcase roles for the entire ensemble. A company does Jewels, in part, to prove that it can. And Pacific Northwest Ballet most definitely can. Try to catch a performance with Louise Nadeau in the Emeralds sectionher individual style meshes brilliantly with the ornate arm gestures that fill this ballet. Nadeau is retiring at the end of this season, so see her while shes still here. SANDRA KURTZ [See Kurtz' review here.] 7:30 p.m. Thurs.-Sat. Ends Feb. 7.