Pool Table Diamonds: How to Use the Diamond System
The diamonds on a pool table are the inlaid markers on the rails, also called sights. There are 18 of them, and they split the table into an even grid: each one marks a quarter of the table's width or an eighth of its length. You use them to find the kitchen line and the foot spot, to repeat practice setups, and above all to aim kicks and banks by counting instead of guessing.
Counting diamonds to aim is what players call the diamond system. It's really a family of formulas, and when someone says "the diamond system" without a name, they usually mean the Corner-5 System for three-rail kicks: the cue ball's starting number minus the first-rail number equals the third-rail number. Below: what the diamonds measure, the everyday ways to use them, the main systems side by side, and step-by-step versions of the two most famous ones.
What the diamonds on a pool table are
The diamonds are sights inlaid in the rail cap. WPA equipment specs call for 18 of them (or 17 plus a nameplate): three on each short rail and six on each long rail, three either side of the side pocket. On a 9-foot regulation table they sit 12 1/2 inches apart, and 11 1/2 inches apart on an 8-foot. They can be round or diamond shaped. The WPA rules define them by position instead of inches: each diamond marks a quarter of the table's width or an eighth of its length, measured from cushion nose to cushion nose, so smaller tables simply space them closer together.
Because a regulation playing surface is twice as long as it is wide, the spacing is the same on every rail: four diamond spaces across a short rail, eight down a long rail, and the side pocket sits at the fourth position. The table is two squares side by side, and that equal grid is what makes the arithmetic work.
One detail trips people up. The specs put the center of each sight 3 11/16 inches behind the cushion nose. So "aim at diamond 2" can mean three different lines: through the diamond itself, at the cushion nose across from it, or in the rail groove where a ball sits frozen to the cushion. Each system says which one it uses. Our kick shots guide has a table for choosing between them by speed.
How to use pool table diamonds
Most players use the diamonds for five jobs, from simple to clever:
| Job | How the diamonds help |
|---|---|
| Find the head string (the kitchen line) | The WPA rules put the head string at a quarter of the table's length from the head rail, which is the line between the second diamonds on the long rails. Ball in hand behind the line means behind that imaginary line. |
| Find the foot spot and center spot | The foot spot sits where the foot string (between the second diamonds from the foot rail) crosses the long string down the middle. The center spot sits between the side pockets. |
| Set up practice shots | Describe any position by diamonds ("cue ball one diamond off the side rail, across from the second diamond") and you can set it up again tomorrow. |
| Aim one-rail kicks and banks | Count diamonds to find the mirror point on the rail. Our guides to kick shots and bank shots show the counts step by step. |
| Aim multi-rail kicks | Number the diamonds and use a formula such as Corner-5 or the Plus System, covered below. |
A quick habit worth building: when you walk up to a shot, read the cue ball's position in diamonds. Once you can name where the balls sit, every system on this page gets easier, because the inputs are already in your head.
Diamond systems at a glance
| System | Shot | Spin | Rule |
|---|---|---|---|
| 2-to-1 (also mirror, equal-distance) | One-rail kicks and slow rolling banks | None | For a corner target, the near-rail number is twice the kicking-rail number (4 to 2) |
| One-third more than twice | Firm one-rail banks | None | Near-rail groove point is 1/3 diamond more than twice the banking-rail point |
| Plus System (Plus Two) | Two-rail kicks, short rail first | Running | Starting number plus short-rail number equals arrival number |
| Corner-5 | Three-rail kicks, long rail first (also two and four rails) | Running | Third-rail number = starting number minus first-rail number |
| Spot on the wall | Three-rail kicks | Running | No numbers: aim at a fixed spot in the room |
| Parallel tracks ("Sixes") | Three-rail kicks to a fourth-rail target | Running | Diamond separation of the first leg plus target diamond equals 6 |
The one-rail systems are covered in our guides to kick shots and bank shots. The rest of this page covers the multi-rail systems.
The Corner-5 System, step by step
Corner-5 came over from three-cushion billiards. It aims a cue ball that goes long rail, short rail, long rail. Three sets of numbers do the work:
| Number | Where it is | How it counts |
|---|---|---|
| D, the starting number | Where the cue ball's aiming line, extended back through the cue ball, crosses the rail behind it | 5 at the corner pocket. Each diamond along the long rail subtracts 1/2 (4.5, 4, 3.5, 3 at the side pocket). Each diamond along the short rail adds 1 (6, 7, 8). |
| F, the first-rail number | The diamond you aim through on the opposite long rail | 1 at the first diamond from the far short rail, counting up toward you |
| T, the third-rail number | Where the cue ball arrives on the third rail (the long rail you started from) | Same count as the first rail: 1 at the first diamond from the far end |
The formula is T = D - F. To use it:
- Pick the third-rail spot the cue ball needs to reach to hit your target ball. Dr. Dave Alciatore suggests assuming the cue ball comes off the second rail at about 45 degrees to find it.
- Lay your cue over the cue ball and read D and F where the line crosses the rails.
- Pivot until D minus F equals the T you need. Example: from the corner (5), aiming through the second diamond (2) sends the cue ball to the third diamond (3) on the third rail.
- Shoot with running english at a smooth, medium speed.
Many tracks reach the same third-rail number: 6 to 3, 5 to 2, 4.5 to 1.5 and 4 to 1 all arrive at 3. That's what makes the system practical. Once you know where one track goes, you know where its whole family goes.
Calibrate Corner-5 for pool tables
Here is the catch most explanations skip. Books often show the 5-to-3 track (arriving at 2) continuing off the third rail into the corner pocket. That's how it plays on a three-cushion table, which is larger, has no pockets and has different cushions. On a typical pool table, Dr. Dave found the 5-to-3 track still arrives at 2, but comes up almost a diamond short of the corner. A track closer to 5-to-2 (arriving at 3) usually reaches the corner instead.
So your benchmark is one shot: from the corner, find which first-rail number sends the cue ball three rails into the opposite corner on the same short rail. Start at 2. Short of the pocket? Lower the first-rail number a little. Long? Raise it. Whatever third-rail number works becomes your corner target for the night, and every track that reaches it heads to the corner.
Adjustments he describes after that:
- Speed and english hardly change where the cue ball meets the third rail. They change where it goes after. Slower runs short of a fourth-rail target, faster runs long.
- Starting numbers below 5 (cue ball farther down the long rail) come up short, so use a slightly smaller first-rail number. From 3.5 he moved the aim about a third of a diamond.
- Clean balls on slick cloth keep sidespin longer than dirty balls on sticky cloth, which stretches the path off the third rail.
The Plus System for two-rail kicks
The Plus System, also called Plus Two, aims kicks that go into a short rail first, then off a long rail. It uses its own numbers:
- Short rail: count by half diamonds from the corner pocket on the far side of the table. The corner is 1, the half diamond is 2, and the three diamonds are 3, 5 and 7.
- Long rail on your side: the corner at the short rail you're kicking into is 0, then 1 through 7 up the table, with 8 at the far corner.
Rule: the long-rail number where your aiming line starts, plus the short-rail number you aim through, tells you where the cue ball's track arrives after two rails. From 3 through 5, it heads to 8, the far corner. From 6 through 2, also 8. Shoot it with a rolling cue ball and running english.
Calibrate with that 3-through-5 shot. Dr. Dave's adjustments, from his Billiards Digest series on the system:
| Result | Fix |
|---|---|
| Cue ball comes up short | More speed or less english |
| Cue ball goes long | Less speed or more english |
| Aiming through large numbers (6, 7) | Tends to come up short: use less english, possibly none, or more speed |
| Aiming through small numbers (2) | Tends to go long: use more english |
Nobody agrees why it's called Plus Two. Dr. Dave lists several theories, including that a kick in and out of the corner pocket shifts two diamonds up the table.
No-math options for three-rail kicks
Not everyone wants to subtract decimals while their opponent watches. Two visual methods get you close.
Spot on the wall. During warm-up, find the line that sends the cue ball three rails into a corner on this table. Extend that line past the table to something on the wall 10 to 20 feet away, a sign or a light. For cue balls between that corner and the side pocket, aiming at the same spot sends the cue ball to the same place. Florian Kohler teaches it this way for PoolDawg, and he notes that the textbook third-diamond aim doesn't work on most tables, which is exactly why you find the spot by test.
Parallel tracks (Sixes). Patrick Johnson's method on Dr. Dave's site: draw the first leg between a diamond on one long rail and a diamond on the other. Three-rail kicks whose first legs are parallel land close together on the fourth rail. Count how many diamonds apart the two ends are (the separation). Separation plus the fourth-rail target diamond (counting the pocket as 0) equals 6. So a separation of 6 heads to the corner, 5 to the first diamond, 4 to the second and 3 to the third.
How to practice a diamond system
Pick one system and one benchmark shot. Mark the cue ball spot with a sticker and shoot it ten times at the same speed and spin, noting where each one lands. That tells you how your stroke and this table differ from the book. Then move the cue ball one diamond, say out loud where it should arrive, and shoot. Predicting first is what makes the numbers stick. Ten focused minutes beats an hour of random kicks, and a notebook of your benchmark results lets you reset quickly on a table you've played before.
Where diamond systems break down
Every system here assumes a specific stroke: rolling cue ball, a set amount of running english, medium speed. Change any of those and the numbers drift. Tables drift too. Dr. Dave singles out Diamond brand tables, especially 7-foot bar boxes and older Red Label 9-footers, as kicking and banking much shorter than other brands; new slick cloth and dry rooms play long, humid rooms and dirty balls play short.
Treat the formula as the first estimate and your benchmark as the correction. Even Dr. Dave notes that most great bankers rely on feel built over years rather than systems. A system is a reference to adjust from, and for most league players that reference is worth having, especially on kicks where you can't see the path. If you want the carom background these systems came from, see our carom billiards explainer.
Sources
- Dr. Dave Alciatore: diamond systems overview
- Dr. Dave: Corner-5 System resources, including Corner-5 Intro (Billiards Digest, November 2010) and Corner-5 Adjustments (January 2011)
- Dr. Dave: Plus System resources, including Plus System Intro (Billiards Digest, August 2010)
- Dr. Dave: why Diamond tables kick and bank short
- WPA Rules of Play (table parts: diamonds, head string, foot spot)
- WPA Recommended Equipment Specifications (rail sights)
Our picks
Links open the current selection and price on Amazon so you can compare real reviews before buying.
Byrne's New Standard Book of Pool and Billiards
Going deeper on Corner-5Robert Byrne's classic guide covers eight-ball, nine-ball and much more, and it's where Dr. Dave points readers for the "Seattle Kid allowance," a correction for Corner-5 shots from cue ball positions where the basic formula drifts. A good shelf reference once the basic formula is second nature.
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Gemscream 2-Piece Dotted Training Cue Ball Set
Keeping your english consistentTwo regulation 2-1/4 inch resin practice cue balls, one with a six-dot pattern and one with a double-sided design. Every multi-rail system assumes the same amount of running english each time, and the dots show you whether you actually delivered it on your benchmark shots.
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YUXMU Pool Table Marker Dots, 240 Pack
Repeatable benchmark shots240 peel-and-stick 35 mm spots made to come off the cloth cleanly. Mark your Corner-5 or Plus System benchmark cue ball positions once, and every calibration session starts from the same spot, so speed and spin are the only variables.
Check price on AmazonFrequently asked questions
What is the diamond system in pool?
It's a set of aiming formulas that number the diamonds on the rails so you can calculate kick and bank lines. The best known is the Corner-5 System for three-rail kicks: starting number minus first-rail number equals third-rail number.
What are the diamonds on a pool table for?
They are aiming and measuring marks. Each diamond marks a quarter of the table's width or an eighth of its length, so you can locate the head string and foot spot, repeat practice setups, and count your way to the right rail point on kicks and banks.
How many diamonds are on a pool table?
Eighteen under WPA specs, or 17 plus a nameplate: three on each short rail and six on each long rail. On a 9-foot table they're 12 1/2 inches apart.
Which diamond system should I learn first?
Learn the one-rail 2-to-1 kick first, since one-rail kicks come up most often. Then add the Corner-5 System for three-rail kicks, and the Plus System if you often get hooked near a short rail.
Why doesn't the 5-3-2 three-rail kick go in the corner?
That benchmark comes from three-cushion billiard tables. On most pool tables the 5-to-3 track still hits the second diamond on the third rail but comes up short of the corner. A track closer to 5-to-2 usually reaches the corner; test it on your table.
Do diamond systems work on 7-foot bar tables?
The formulas work on any table with the standard 2-to-1 playing surface, but conditions vary a lot, and Diamond brand bar boxes are known for kicking and banking short. Calibrate with a benchmark shot before you trust the numbers.
Do professional players use diamond systems?
Some do, especially for multi-rail kicks. Dr. Dave Alciatore notes that most great bankers rely mainly on feel developed over years, using systems, if at all, as a reference to adjust from.
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