Cue sports playing nine-ball. Snooker balls are smaller than American-style pool balls with a diameter of 52.5 mm ( in), and come in sets of 22 (15 reds, 6 "", and a cue ball). English billiard balls are the same size as snooker balls and come in sets of three balls (two cue balls and a red, an object ball). Other games, such as bumper pool, have custom ball sets. Billiard balls have been made from many different materials since the start of the game, including clay, bakelite, celluloid, crystallite, ivory, plastic, steel and wood. The dominant material from 1627 until the
Rules of snooker awarded, see below). If a player fails to pot a ball "on", whether a red or a nominated colour, the other player will come into play and the balls "on" are always the reds, as long as there are still reds on the table. The alternation between red balls and colours ends when all reds have been potted and a colour is potted after the last red, or a failed attempt to do so is made. All six colours have then to be potted in ascending order of their value (yellow, green, brown, blue, pink, black). Each becomes the ball