A carom set cannot be identified by colour alone. Check the discipline, diameter and matching of all three balls. A correct catalogue size does not by itself certify the condition of the set on your table.
Official carom geometry at a glance
Dimensions describe the free playing surface, not the outside furniture size.
Read the specification for the right game
The Danish federation's copy of the UMB rules, effective 1989, gives carom diameter as 61–61.5 mm, mass as 205–220 g unless another mass is approved by the committee, and a maximum 2 g difference between the heaviest and lightest ball. These are rule limits, not an invented manufacturing tolerance of 61.5 ±0.1 mm.
The WPA equipment document gives the nominal pool diameter as 2¼ inches, equivalent to 57.15 mm, and mass as 156–170 g. WPBSA's 2024–25 snooker rules specify 52.5 ±0.05 mm and no more than 3 g between the heaviest and lightest ball in the set. They do not prescribe a single 142 g mass in that provision. Pool and snooker are not the same size; English billiards has its own matching provision and must not be substituted for the snooker rule.
An individual weight limit does not guarantee a matched set
In this invented weighing exercise, every ball in set A is within 205–220 g, yet 213 − 210 = 3 g exceeds the cited carom spread. Set B has a 212 − 210 = 2 g spread and meets that condition on the stated readings. It is not thereby certified round, correctly sized or approved for an event. All table values are grams.
Weigh clean, dry balls on the same checked scale, record each colour and calculate maximum minus minimum. Include the instrument's resolution and uncertainty: a coarse kitchen scale reading exactly 2 g apart cannot establish compliance at the boundary. Do not average away a mismatch or replace one ball with an unrelated single solely because its colour looks right.
| Example set | White (g) | Yellow (g) | Red (g) | Largest − smallest (g) |
|---|---|---|---|---|
| A: spread exceeds limit | 210 | 211 | 213 | 3 |
| B: spread at limit | 210 | 211 | 212 | 2 |
What to ask before buying or replacing
Request the exact three-ball carom model, stated diameter and material, set-matching information, care instructions and the supplier's return terms. If buying for an event, confirm the required approved equipment with its organiser. A marketing label such as professional, black or premium is not a measurement and does not establish a ranking between models.
For a replacement ball, ask the manufacturer or supplier about matching the existing set's model, size and wear. A new ball alongside two worn balls may differ even when the box lists the same nominal size. We have not measured competing brands or established a best-value winner; appearance and price alone are insufficient evidence.
Inspect symptoms without diagnosing from one roll
Clean the set according to its instructions and inspect it under good light for chips, cracks and persistent surface damage. Stop using a visibly damaged ball and ask the supplier to assess it. A diameter check needs a suitable instrument, several orientations and knowledge of measurement error; one calliper reading does not prove full roundness or balance.
If a slow roll veers, compare another ball on the same path, then repeat in the opposite direction and elsewhere on the table. Record which ball, route and surface condition change the result. Cloth, level and delivery can also affect a roll. Spinning a ball on the cloth is not a certification test, and a different rebound is not proof that the ball is defective. Do not sand a ball to make it match.
Use the care method for that product and event
Aramith's instructions distinguish routine Ball Cleaner from Restorer for stubborn marks; the restorer step is followed by cleaner. The manufacturer permits finishing with a dry cloth, paper or an electrical buffer as described in its directions. This does not approve every machine, compound or aggressive polishing method. Its liquids are described as silicone-free.
Keep the work away from the playing cloth, follow the exact product directions and leave no unwanted residue. Competition rules also matter: the cited WPA pool specification excludes wax and slippery surface treatments, so a care recommendation must not be transferred indiscriminately between disciplines. Store the set protected from impacts and inspect it when play changes; neither a universal replacement date nor guaranteed diamond-system accuracy follows from a brand name.