The German-born, Bay Area–dwelling designer has enviable taste in books, films, and, not surprisingly, colored stones Jewelry designer Petra Class trained as a silversmith in her native Germany, but you’d swear in a previous life she was a painter. Her gallery of gemstones looks like an artist’s palette: cerulean-colored opals, ultramarine-hued lapis, viridian-green tourmalines, and more. Then there’s her choice of metal—rich 18k and 22k yellow gold—which outlines each stone like a gilded picture frame. Can you blame us for ­describing her pieces as works of art? Age: 60 Number of years in the biz: 40 Number of employees you oversee: Three. Family and pets: Husband and adult son; my cat passed away of old age a year a