Since they first became popular in the 1940s, sequins have been the shady lady of fashion—expensive, slinky and frivolous. But in the decade just begun, declare two young designers, sequins will supply smart sparkle at work, the mall, virtually anywhere.

Sequined clothes "are conversation pieces. They give you a zap," says Jeanette Kastenberg, 28 (whose labels bear only her first name). "Why wear them only in the evening? Why not get up in the morning and put on something that's going to make your day?" Stretching tradition like a length of Spandex, JEANETTE stitches her sequins onto swimsuits, gym shorts, jumpers and bolero jackets. "I'm very playful; I want to have a good time and that's what my clothes are," says the Montreal native, who began her New York City career as a fashion-house receptionist. "Who says it's outta whack? It looks right. It's fun. I say, 'What is fashion? It's what looks good on you.' " Free-thinking converts to the Jeanette message include Deborah Harry, Jessica Lange and Michelle Pfeiffer.

Indiana-born C.D. GREENE says he designs his shim-mery body-hugging dresses for "a woman who is 25 or even 55 and doesn't want to look like her daughter but does want to look contemporary and exciting while not spending an extraordinary amount of money." Before switching to fashion, Charles Dennis Greene, 32, studied art and architecture at the Art Institute of Chicago, a discipline that imbued him, he says, "with a real feel for sculptural shapes." He gives his clothes a smooth, flattering fit ("I work with pattern-makers very closely") and dots them with small round silver paillettes or mirrors in various sizes. "These clothes should absolutely be worn day-into-evening," he urges. "Have fun with your clothes. Rotate them. It makes you not take fashion quite so seriously."