"Jewelry has to be juicy, not dry," says John Loring, senior vice president and design director of the legendary American retail palace, Tiffany & Co. Loring will be helping to celebrate Tiffany's 150th anniversary, appropriately, in the home of the nation's gem collection, the Smithsonian's National Museum of American History.

An illustrated lecture will be presented by the Smithsonian Resident Associate Program on Monday, Sept. 21, at 8 p.m. in the museum's Baird Auditorium. It will feature such wonderful audacities as Gypsy Rose Lee's fire opals, Mary Todd Lincoln's seed pearl necklace and bracelets and the sterling silver bicycle commissioned by Diamond Jim Brady for Lillian Russell.

Loring cites actress Audrey Hepburn as Tiffany's patron saint, and says that while the name Tiffany has become a term synonymous with luxury, the company's attitude toward its merchandise and the public is "democratic -- we've never been a snooty little shop with a bunch of guards at the door. We're like an emporium, a place to go and dream and have a good time. We provide props that offer pleasure and fun and elegance."

At what cost, one wonders? Well, for a mere $5, you can have "Tiffany Table Manners for Teenagers," a book written by longtime owner and (now retired) chairman of the board Walter Hoving. The most popular item? An all-purpose lead crystal wine glass for $12. And if you revel in "Breakfast at Tiffany's" daydreams as Holly Golightly did -- and have the wherewithall to back them up -- you can pick up a diamond solitaire ring or maybe a ruby and diamond necklace for, say, a cool million.

Most of the Tiffany designs that will be discussed are historic, either museum objects or pieces from private collections. The more current designs of Elsa Peretti, Paloma Picasso and Jean Schlumberger will also be featured.

Tickets for Tiffany's "Double Diamond Jubilee" are $6 for members of the Smithsonian Resident Associate Program, $7.50 for nonmembers. For further information, call 357-3030.