When someone refers to a woman’s rock, it usually means she’s showing off a pretty major diamond. But if it was the early 1970s—and designer David Webb’s ­jewelry—she was probably wearing just that: a rock. Rock crystal, that is. Take this 1971 photo of model Lauren Hutton in rock crystal and coral cuffs with matching ear clips all by Webb.The New York City–based ­jeweler had started incorporating rock ­crystal into many of his pieces around 1970. “The country had gone into a financial tailspin, so people were dialing it down, so to speak,” says Ruth Peltason, author of David Webb: The Quintessential American Jeweler (due out this month). “Rock crystal is luminous, pretty, feminine. It suddenly became so chic and he did gangbuster business in it.” Webb would carve the rock into different shapes—even beads, which acted like prisms when in direct light. The New Yor