Pool ball sets can range from $30 to $200. So what makes the difference? The higher priced balls are made of phenolic resin while cheaper balls are typically made of polyester. Phenolic resin is harder and more burn resistant than the cheaper materials. This increases the durability of the balls so they will last longer than cheaper sets. The highest quality balls are the Aramith Tournament Belgian Billiard Ball Set, Aramith Super Pro's and Brunswick Centennials . These are made in the same factory and play identically, but there are subtle aesthetic design differences.
Another difference in the price ranges is build quality. On some of the cheaper pool balls, the numbers and certain design elements are painted on or inlaid. This makes them prone to coming off or falling out after too much play or if they jump off the table and hit the ground. Higher quality pool balls have the center precision engraved with a solid core that runs all the way through the ball so there's no chance of them falling out.
Finally, higher quality pool balls are made with tighter tolerances. These specify the roundness, the diameter, and the weight, among other characteristics. This makes the balls roll truer so they are more predictable. It also helps if a ball goes missing so you can find a replacement ball that will fit in with your set. Having a mismatched set will make some trick shots impossible and it's one more thing to worry about when you're setting up a shot.
Cue balls are special for a variety of reasons. First, it's the only ball you ever really hit with your cue stick. It's the most important ball because you want to control where it goes to make your next shot easier, so you hit it at different speeds and apply different spins to it. One of the more prominent cue balls is the Aramith Pro Cup Cue Ball , distinguished with its six red dots, also known as the "measles" ball. These dots help you distinguish the spin on the cue ball and can help you learn how long the spin lasts on the ball. It's also easier for the audience to see the spin you put on the ball too.
Cue balls can also be different if you're playing on a coin-op table where it needs to be separated from the object balls in case of a scratch. The most common case is that the cue ball is bigger and weighs a little more than the standard 6 oz. This makes it more difficult to apply spin to the cue ball, especially draw. Another typical method is that the cue ball will have a magnet in the center of it. This can change the weight of the cue ball and, in low quality balls, affect its balance so it wobbles. Finally, there is a new system from Diamond Billiards where the table has optical sensors to distinguish the cue ball, so you can use a regular cue ball on it. In any case, be aware of these variables when trying to perform trick shots or just going from table to table playing pool. I like to bring my own cue ball to shows so I know for sure what I'm using.