Invisible settings, also known as serti invisible, are comprised of stones that have been calibrated to very close tolerances and are cut with grooved girdles that are locked into a thin wire framework. This allows large areas of jewelry to be coated “seamlessly” with gemstones. There are no prongs, bezel or other visible means of holding the stones. This process was perfected by Van Cleef & Arpels and patented by them in 1933.