Pool ball colors

Three primary colors:
1 & 9 = Yellow (primary)
2 & 10 = Blue (primary)
3 & 11 = Red (primary)

Three secondary colors:
4 & 12 = Purple (blue+red)
5 & 13 = Orange (red+yellow)
6 & 14 = Green (yellow+blue)

One tertiary color:
7 & 15 = Maroon (purple+red)

Two all-or-nothing colors:
8 = Black
Cue = White

Source: http://billiards.colostate.edu/threads/balls.html