First a little history about billiard balls.
According to the article on Wikipedia, the earliest balls were made of wood, and later clay (the latter remaining in use well into the 20th century).
Ivory was used for a period, but by the mid-1800s, elephants were being slaughtered for their ivory at an alarming rate, just to keep up with the demand for billiard balls. No more than eight balls could have been made from a single elephant.
Inventors were challenged to come up with an alternative material that could have been used to manufacture billiard balls.
In 1869 a composition material called cellulose nitrate was used for billiard balls. (US patent 50359, the first American patent for billiard balls).
By 1870 it was commercially branded celluloid, the first industrial plastic. The nature of celluloid made it volatile in production, occasionally exploding, which extremely made this first plastic impractical.
Imagine that, Exploding Billiard Balls. Wow! You shoot in the 8 ball and it blows up.
Today's balls are cast from plastic materials that are sturdy resistant to cracking and chipping. Currently saluc, under the brand names "Aramith" and "Brunswick Centennial", manufactures phenolic resin balls. Other plastics and resins such as polyester (under various trade names) and clear acrylic are also used, by competing companies such as "Elephant Balls"
Thanks to Wikipedia for the above history lesson. You may want to search billiard balls on Wikipedia for the full story. You will even find links for more information on all the materials used and tested.
Billiard balls used to be pretty common as far as color. The number balls were all pretty much the same colors in most sets of balls. I have seen some pretty wild colors over the past several years.
You can read all about ball sizes and colors by visiting Wikipedia dot org and typing billiard balls into the search box.
The main thing that I watch for is the size and weight of the cue ball. Older style bar tables used to have a larger cue ball. This large cue ball is harder to draw and back up and follows like a large truck.
We only have a couple of tables left with those large cue balls here in Pueblo Colorado. I can say from personal experience that the game changes due to an over sized cue ball.
The other thing to watch for is the mud ball. This is a heavy cue ball that does not roll anywhere very good. The same as the big ball, the mud ball follows much better than it draws.
The valley cue ball which is used in Valley brand bar tables has a magnet in it. This is how the table knows to return the cue ball in the opposite end of the table than the other billiard balls. (head spot)
This magnet or weight can be off center and cause the cue ball to roll funny or crooked.
My favorite cue ball is the red circle. This ball has a small red circle on a white ball. The newer Smart Diamond tables can detect this red circle for proper cue ball return to the head of the table.
Did you know that you can buy trick balls? These can be kind of funny the first time you slip them in the game on someone. These balls are weighted off center and take some darn funny turns. I recommend a trick cue ball or 8 ball if you want to prank your friends.
To your run out success.