How to Read Diamonds on a Billiards Table

TL;DR: Every long rail of a carom table carries seven diamonds — small markers of mother-of-pearl, brass or dark wood inlaid into the wood above the cushion rubber (some tables have five). You count them 1 to 7 starting from your own end of the table. Those diamond numbers are the foundation of every calculation in the diamond system.

What diamonds are and why they matter

Diamonds are small inlaid markers set into the wood that frames the cloth, sitting just above the cushion rubber. They never touch the ball’s path — they are pure visual references. Their placement is not decorative: each diamond marks the exact position of one-eighth of the table’s length, which lets your brain calibrate distance without physically measuring anything.

Without diamonds, calculating a rail rebound would be like navigating with no coordinates. With them, any system — Corner 5, Plus 2, the Korean 5-and-a-half — can translate a geometric angle into an observable physical point. Diamonds are to the carom player what the staff lines are to a musician: a shared grid that makes communicable what used to be pure intuition.

Standard numbering (the extended Korean system)

The numbering used most widely on the professional circuit assigns consecutive whole-number values to every diamond on the table, running around the four rails as one continuous number line:

Your own long rail:        1   2   3   4   5   6   7
Far short rail:            8   9  10
Opposite long rail:      11  12  13  14  15  16  17
Near short rail:         18  19  20
Your long rail (return): 21  22  23  24  25  26  27

Each increment of 1 corresponds to one physical diamond on the frame. The corner is worth 0, not 1. This continuous numbering is what lets you compute long around-the-table paths by adding or subtracting values without ever switching systems.

Typical beginner mistakes

1. Counting the corner as 1: the corner is 0, not 1. The first real diamond sits at 1/8 of the rail length.
2. Confusing 5-diamond tables with 7-diamond tables: older tables carry only five diamonds per long rail, and the arithmetic changes accordingly.
3. Using the diamond as an exact point of impact: diamonds are references for your eye, not physical targets. The ball touches the rubber, not the diamond.
4. Mixing the departure diamond with the contact diamond: they are different values in the system — you subtract them, you do not add them.
5. Forgetting visual perspective: from two metres away two diamonds look like they almost touch; crouching and sighting from the side unlocks the perspective.

Reading drill — 30 minutes a day

To internalise the numbering, reading this article is not enough — you have to repeat the mechanical drill across several sessions. It fits inside any warm-up routine.

1. Place the red ball at a random position on the table.
2. Out loud, identify which two diamonds the ball sits between.
3. Estimate the fraction to one decimal (for example, diamond 4.3 = between 4 and 5, closer to 4).
4. Move the ball to another position and repeat.
5. After 30 repetitions, try it without looking at the frame — identify the position with peripheral vision alone.

Thirty minutes of this drill over a week makes diamond-system calculations roughly three times faster, because it removes the ‘hunt for the diamond’ bottleneck that otherwise sits in front of ‘calculate the contact’. Pair it with a structured beginner drill plan and the numbers become second nature.

Professional tables versus salon tables

Not every table has the same number of diamonds. Professional tournament tables (UMB, the European federations) carry seven diamonds per long rail and three per short rail — twenty diamonds in total around the table. Old salon tables (especially in Spain and Italy) often have only five per long rail, which complicates translating systems that were calculated on the seven-diamond basis. Asian tables (Japan, Korea) follow the European standard. See our table dimensions guide for the full measurements.

If you regularly play on a non-standard table, devote one session to re-mapping the numeric values: count the diamonds physically and assign them proportional values (on a 5-diamond table each diamond is worth 1.4 on the standard scale of 7). Without that adjustment the calculations will hand you contacts that are systematically displaced.

Diamonds and other geometric systems

The diamond system is not the only reference frame. Alternative systems are built on other divisions of the cloth — the line system (Bertus van der Smissen), the clock system (Kim Haeng-jik), the triangle method used by some Turkish professionals. They all share the same need: a visual grid that translates angles into points. Diamonds win because they are universal, physically present, and require no extra markings to memorise. For the broader picture of how these reference frames fit together, read the three-cushion aiming systems overview, and apply the numbering directly on a worked layout like the around-the-table position. Unsure of a term? The glossary defines every reference word used here.

For the full path from rail reading to a complete shot plan, work up through the three-cushion complete guide.

Practise without a table: plug any cue-ball position and target into the free diamond calculator and watch the rail numbering from this guide turn into a concrete first-cushion aiming point, with the full three-cushion path drawn for you.