The moving element

Most jewelry holds still. This family does not, and its oldest member is very nearly a machine. The zip fastener was new to couture in the late 1930s when the Duchess of Windsor suggested a jewel based on one; Renée Puissant, artistic director of Van Cleef & Arpels, had a jewelled zip patented in 1938, and more than ten years of engineering passed before the first necklace left the workshops in 1950. Pull its tassel and it closes into a bracelet.

Geneva set stones free. In 1976 Chopard let diamonds float loose behind sapphire glass on a watch, the start of a line it calls Happy Diamonds and traces to sunlight in the mist of a Black Forest waterfall. Valérie Messika carried the floating diamond onto the wrist in 2007: Move, three stones sliding in an open gold cage, came from a childhood memory of her father passing diamonds between his fingers. Smaller motions run through the other houses. The sugarloaf cabochons of FRED's Pain de Sucre click in and out of their mounts, Piaget's Possession ring turns on its axis under the thumb, and the two ends of Boucheron's Jack snap together like a plug into its socket.