The word “rock” is sometimes used to describe an expensive gemstone, but not many real rocks are used in high-quality jewelry. “Rocks” (e.g., diamonds) are single minerals; gem rocks are made up of two or more minerals and are usually fashioned into ornaments such as candlesticks or carved animals. Only a few gem rocks—lapis is a good example—are considered standard jewelry items.

These days, more designer jewelry pieces are being set with unusual gems, with many designers favoring ornamental minerals and rocks. Los Angeles studio jeweler Beth Rosengard uses drusys of white chalcedony, agate, and chrysocolla in her wearable art. When Rosengard uses calcite-on-basalt—which to most jewelers might look only mildly interesting—the stuff becomes fine jewelry. Some of the other unusual gems starring in Rosengard’s designs are psilomelane drusy, yowah nut opal, ammolite, and apache chrysocolla. As Rosengard explains it, the material helps determine the design of the jewelry.

Stephan Hoglund of Stephan Hoglund Studio, Grand Marais, Minn., is another designer who uses unusual gems. But Hoglund’s gems really are rocks—Lake Superior beach rocks. It’s tough to resist plucking a nice beach rock out of the sand, but not many people would put it into jewelry. For Hoglund, however, the beaches lining Lake Superior are perfect locales to find jewelry rocks, made smooth by the rough waters at the shoreline.

Bill Gangi of Multisensory Arts  in Tucson also knows his beach rocks—he’s been collecting and selling them for years. Gangi and others have been using beach rocks—including sea glass, graphic granite, and black basalt—for at least a decade.

Gangi gathers a wide assortment of other nontraditional gem materials, not only for his own use but also for other jewelry designers. “We specialize in natural surface stones,” says Gangi, who is excited about a new find of intensely colored and iridescent smithsonite. “It has a satin-like coxcomb crystal surface and rainbow iridescence playing over the surface,” he explains.

Smithsonite is one of those “GIA B-chart” gems, usually found in delicate pastel pale blues, greens, and pinks, shaped like tiny domed hills, and commonly seen in mineral displays at natural history museums. “This new material is deep gem-silica blue, emerald green, purple, magenta, orange, or white, [and] also happens to be iridescent,” says Gangi. The surface of the material has an “oil slick” sheen. He has pieces up to a foot long, in intense colors, and can cut pieces for jewelry up to several inches in size—previously unheard of for smithsonite.

“It’s a sickness,” confesses Gangi, referring to his passion for unique gem materials. “We love rocks.”

Gangi says he’s working on a new find of rocks that contain pockets of what he says look like tiny cliff dwellings. He plans to show the material in Tucson in February.