Channel setting is a style of gemstone setting that involves placing a line of stones girdle-to-girdle in a groove so that there is no metal between them. No prongs, beads or bezels are required to hold the stones in place. The edge of the "channel" is smoothed over the stones to secure them.
Platinum Art Deco inspired ladies engagement ring with eight graduated sapphires channel set into the shoulders. Image courtesy of Lang Antiques