How to Use the Sights on a Pool Table
The inlaid objects along the rails on a pool table are not merely for decoration. These are sighting marks, meant to improve the accuracy of your shots. They can be round pearl colored objects, diamonds, or other custom shapes. In a game of pool or billiards, however, these marks are most commonly referred to as "diamonds," and take advantage of the common geometry shared by all regulation pool tables to aid you in banking a shot off of multiple rails.
Banking a Shot off of Two Rails
Count the diamonds along the long rail, starting from the one nearest the cue ball, to your intended target. This will help you bank a shot off of the short side, followed by the long side, prior to hitting your target.
Starting from the opposite side rail (the second bumper you will bank off of), count that same number of diamonds along the end rail (the first bumper you carom off of).
Aim and shoot your cue ball at the diamond you arrive at using running English, in which you strike above and to the side of its center, away from its first target. This will give it a sidespin which will cause the cue ball to rebound from an object ball or cushion at a narrower angle and at a faster speed.
Banking a Shot off of Three Rails
Plan a trajectory for the cue ball to bounce from a long rail, then a short, then the other long before hitting your intended target. Note the spot on the second long rail where the third and final bounce must occur before hitting your target.
Count the diamonds leading to it, starting from the end you make your initial shot towards, and subtract two. Count this same number of diamonds on the other long rail (the first bumper that the cue will hit) in the same direction.
Aim through and strike the cue ball into the diamond you arrive at with no English. If you use running English, add another half of a diamond to arrive at the spot you should aim at.
Always aim through the center of the diamond itself, not the point on the bumper that lies in front of it.
No two billiard tables are alike. Perform many practice shots to get to know how firm the bumpers are, the friction between the table surface and the balls, and other minor factors that can affect the trajectory of a banked shot.
Jeff Cunningham has written on science and technology since 2007. He has co-authored volumes on science education and offered commentary on spaceflight on the Google Lunar X Prize blog. Cunningham has a Bachelor of Science in aerospace engineering from the University of Central Florida.