Professional Ping Pong Balls
The official rules of ITTF handbook determines that standard balls should maintain these abilities:
The diameter of ping pong balls should be 40mm, as per the official regulations.
The weight of the ball should be between 0.0959 ounces. The mean is taken over a sample, and the mean should be between 0.095945 ounces.
Goes without saying but the balls should be perfectly spherical. The circular shape of the ball is measured between the minimum and maximum diameter and for the celluloid balls it should be less than 0.0137795 inches and for the ABS balls, it should be less than 0.009842 inches.
This also measures the roundness of the table tennis ball but in addition it measures the wall thickness also. You can test your balls by rolling the ball down a slight hill and observed whether it rolls down in a straight line or deviates sideways.
Bounce consistency is also a factor in the quality of ping pong balls. This is determined by dropping the ball from a height of 12 inches or one foot on a solid surface and if the ball returns to a height of ten inches, you can consider it a 3–5 star Quality Ball.
Ping pong balls should be fairly hard, measured by a mechanical device that creates a pressure point with a regulated amount of force.
The 3-star ping pong balls have all of these traits optimized. Three Star quality is why professional balls are far more expensive than the ordinary Beer Pong Balls or those training balls you can buy from AMAZON.