Stone settings
A setting is the metal structure that holds a gem. Its design decides how much of the stone shows, how much light reaches it and how well it survives knocks. Prong settings, also called claws, bend thin metal arms over the girdle, the widest edge of the stone. GIA notes that six prongs hold a stone more securely than four and protect the girdle better. Tiffany & Co. dates its raised six-prong solitaire to 1886, with the metal largely hidden so the diamond floats above the band. A bezel wraps a continuous rim around the girdle instead, trading side light for protection.
Other settings group small stones. In a bead setting, small pieces of metal raised from the surface act as prongs. Pavé, from the French for paved, sets stones so close that neighbors share a bead; micro-pavé does the same work under a microscope. A channel setting holds a row of stones between two parallel metal walls, and a halo rings a center stone with small ones.
Three settings hide metal. Niessing dates its Spannring, or tension ring, to 1979, a contested attribution resting on the maison's own account; the shank alone grips the stone by spring pressure. Van Cleef & Arpels patented the Mystery Set in 1933, sliding grooved stones onto gold rails so no metal shows on the surface. A flush, or burnish, setting sinks the stone into a seat and presses the metal over its girdle.