Naomi Nomikos, right, has run the tiny sales floor at Bardith since she was hired and given a crash course in 18th-century pottery and porcelains by the shop's longtime owner, Edith Wolf, 15 years ago. Here, Ms. Nomikos assists a drop-in client, Wendy Posard, a designer from San Francisco who was driving up Madison Avenue and made an unscheduled stop after she noticed the quality of the antique china in the display windows.