Faceted Green Sardonyx Agate Bead StringPrice is for per 15 inch string of these natural beads. Each bead measures about 12mm x 8mm x 8mm, but sizes in the string will be slightly different, as will patterns. About 30 beads to the string. No gemstone is more creatively striped by nature than agate, technically, chalcedony quartz that forms in concentric layers in a wide variety of colours and textures. Each individual agate forms by filling a cavity in its host rock, resulting in round