Judith herself collects colorful Scottish Monart glass from the 1920s as well as sparkly vintage jewelry like the gold-plated sun-face brooch pinned to her blouse. “People often stop me to ask about this Joseff-of-Hollywood pin,” says Judith, who gently jiggles the vintage brooch to make the twinkly rhinestone eyes move. “The exciting thing about costume jewelry is that you can stumble across something very individual for not very much.” Prices depend on designer names and workmanship. Collectors pay big for pieces marked Chanel, Schia- parelli, or Haskell. But just how the pieces were made counts, too. For instance, are the stones glued or prong-set? Prongs push prices upward (and more prongs mean higher prices).

Her admiration for fetching vintage costume jewelry is contagious. “They are at least equal to or better than the precious equivalent,” notes Judith. “Many of those who designed costume jewelry had earlier been designers for fine jewelers such as Cartier and Van Cleef,” she adds, pointing out that Frenchman Alfred Philippe moved from the real thing to vintage bling (Trifari) in 1930.

Despite the sweltering heat, Judith speeds up when she spots a glimmering constellation of jewelry : chandelier earrings, crystal bead necklaces, and sprays of dazzling rhinestone brooches.

Vintage vendor Jeanne DeSantis is barricaded behind velvet-lined trays of gorgeous goodies and customers two-deep. “ Rhinestones rule,” she says, by way of a greeting.

We wade into the crowd and meet Elizabeth Gavais-Miller, a personal shopper for Bergdorf Goodman, who hopes to reclaim some of the family jewelry . “My grandfather was jeweler Benjamin Bogoff, and I’m trying to buy back as many of his period rhinestone pieces as I can find,” explains Gavais-Miller, who wears her fabulous fakes to work at the posh Manhattan department store.

Gavais-Miller is in good company. A glass-gemstone bangle dangled from the wrist of the Duchess of Windsor (American Wallis Simpson), a triple-strand faux pearl necklace framed the face of Jackie O, and diamonds made of paste sparkled on Marilyn Monroe.

There’s no need to convince Judith, who literally wrote the book on Costume Jewelry (DK Publishing, $35). She sifts through dozens of trays before finding a delicate mother-of-pearl necklace and bracelet, circa 1930. At $35 for the no-name pair, Judith is clearly delighted.

“It’s sweet,” she says admiringly as the dealer wraps it up.

This July, dealer DeSantis will again display her beauteous bijouterie at Brimfield, next to Collin’s Apple Barn. We reached her by telephone at her home in Sylvan Beach, New York, as she was shuffling boxes in preparation for the trek to Massachusetts.

“Colorful rhinestone brooches are in this year,” she says, “but Bakelite is dead.” Thanks to changing tastes, Bakelite (the first synthetic plastic, patented in 1907) presents a real buying opportunity for impecunious collectors in love with smooth, glossy Art Deco bangles.

But price-guide guru Judith tempers my enthusiasm to corner the market on Bakelite. “Don’t buy antiques and collectibles as an investment,” she cautions. “If they appreciate, that’s good. But you should buy it because you love it and can’t live without it.”

Suddenly, I hear those vintage sprinklers calling—psst, psst, psst, psst.