When Marilyn Monroe cooed "Diamonds are a girl's best friend" in 1953's Gentlemen Prefer Blondes, she sounded convincing. What made her look convincing, however, were not diamonds at all but fabulous fakes made by costume jewelry designer Joan Castle Joseff, better known as J.C. Along with her late husband, Eugene, the High Priestess of Paste once created nearly all the razzle that dazzled Hollywood and its most dashing dames, from Greta Garbo's Camille to Elizabeth Taylor's Cleopatra.

Today, with the prevailing '90s notion that it's gauche to be garish, the call for Joseff's gems is fading. "The heyday for our business was in the '30s and '40s, when people really dressed up and wore jewelry," says J.C, a petite septuagenarian who has run Joseff-Hollywood in Bur-bank, Calif., since Eugene died in a plane crash 42 years ago. "Those days are gone."

But not entirely forgotten. This week, Joseff's was called back to glory in People Like Us, the NBC miniseries based on novelist Dominick Dunne's pulp send-up of '80s flash and cash. Thanks to costume designer and longtime Joseff's fan Buffy Snyder, leading lady Connie Sellecca will shimmer in jewelry once worn by Rita Hayworth and Bette Davis and in an "amethyst" necklace, bracelet and earring set worn by Vivien Leigh in Gone with the Wind. "I'll never forget the first time I walked into Joseff's," recalls Snyder. "It was like a treasure chest of history. They have heirloom pieces that are a statement of real elegance. And they photograph like the real thing."

Usually better. "When I was doing Dynasty," says designer Nolan Miller, who dressed the vixens in both Dynasty and Vie Colbys, "I borrowed a $400,000 diamond necklace from Tiffany's, but it wasn't big enough, so I went to Joseff's for everything." On-camera the larger-than-life baubles, crafted from a variety of Czechoslovakian and Austrian stones unavailable today, outshine genuine gems. But that's only part of the draw. A special antiqued-gold-and-silver-plating method eliminates the reflected glare of movie lights.

Fans have long clamored to own Joseff's creations—which J.C. loans out but almost never sells. In 1964, J.C. allowed Debbie Reynolds to buy a copy of the "cigar band" ring she wore in The Unsinkable Molly Brown. Not quite so appreciative was Elizabeth Taylor, who, while filming Cleopatra, blew her top when the belt J.C. measured her for on a Friday was already too tight the following Monday. More recently, J.C. was offered $35,000 for the cigar case Clark Gable used in Gone with the Wind. "But I won't sell it," she insists.

J.C., who lives in Toluca Lake, Calif., keeps the Joseff-Hollywood collection of more than 3 million necklaces, brooches, tiaras, earrings and breastplates warehoused in nearby Burbank. in individually labeled rectangular boxes that keep the trinkets dust free. Her main source of income these days isn't nearly as glitzy: 95 percent of it comes from the aircraft-parts company, founded by her husband in 1931, that uses the same casting method developed for the jewelry. Although J.C. is saddened by the passing of paste, she hasn't let it take the sparkle out of her life. "Not me," she quips. "I'm going to die with my boots on." And, of course, dripping in jewels.

—Karen S. Schneider, Marie Moneysmith in Los Angeles