Dating billiard balls
According to WPA/BCA equipment specifications, the weight may be from 5.5 to 6.0 oz (160–170 g) with a diameter of 2.250 in (57.2 mm), plus or minus 0.005 in (0.127 mm).
In baseball pocket billiards, the ball set is extended to 21 balls, in which the 16 ball is black and white, while balls 17 through 21 have no special design, but look exactly like balls 9 through 13, respectively, except for their numbers.
Snooker balls are technically standardized at 52.5 mm (2.07 in) in diameter within a tolerance of plus or minus 0.05 mm (0.002 in).
No standard weight is defined, but all balls in the set must be the same weight within a tolerance of 3 g (0.11 oz). Snooker sets are also available with considerably smaller-than-regulation balls (and even with ten instead of fifteen reds) for play on smaller tables (down to half-size), and are sanctioned for use in some amateur leagues.
Rarely in the US, some pool tables use a smaller cue ball instead.
Modern tables usually employ a magnetic ball of regulation or near-regulation size and weight, since players have complained for many decades that the heavy and often oversized cue balls do not "play" correctly.
By 1870 it was commercially branded Celluloid, the first industrial plastic.
(See snooker for more information on ball setup.)The colour balls are sometimes numbered American-style, with their point values, for the amateur/home market, as follows in the adjacent table.In WPA blackball and its predecessor WEPF or English eight-ball pool (not to be confused with the games of eight-ball or English billiards), fifteen object balls again are used, but fall into two unnumbered since there is no reliable way to identify particular balls to be pocketed.Because they are unnumbered they are wholly unsuited to certain pool games, such as nine-ball, in which ball order is important.Sorel cement, invented in 1867, was marketed as an artificial ivory), John Wesley Hyatt invented a composition material in 1869 called nitrocellulose for billiard balls (US patent 50359, the first American patent for billiard balls).It is unclear if the cash prize was ever awarded, and there is no evidence suggesting he did in fact win it.