TL;DR: Official three-cushion (carom) balls measure 61.5 mm in diameter — noticeably larger than the 57.15 mm pool/snooker ball — and weigh roughly 205-220 g per ball, with all three balls in a set matched to within a couple of grams. Modern tournament balls are made of phenolic resin (Aramith), which gives the density, hardness, and elastic rebound that make diamond-system calculations repeatable. For serious play, an Aramith Tournament or Super Pro set is the honest sweet spot; cheap polyester or acrylic sets warp, lose roundness, and quietly break your aiming math.
What makes a carom ball different
Carom billiards — the family that includes three-cushion, straight rail, and balkline — is played on a table with no pockets, using only three balls. Because there are no pockets to swallow the cue ball and no need to pack fifteen objects into a rack, the carom ball is built bigger and heavier than its pocket-billiards cousins. That larger mass and diameter is not cosmetic: it changes how the ball stores and releases energy at the cushion, and that rebound behavior is the entire foundation of three-cushion strategy.
A regulation carom set is exactly three balls:
- White — one player's cue ball.
- Yellow — the other player's cue ball. Many modern sets supply a spot ball (yellow or white with two small dots) so the cue ball's spin and rotation are easy to read; plain yellow is also legal and common.
- Red — the shared object ball.
There is no numbered rack, no break ball — just three precisely matched spheres. That is exactly why their specifications matter so much: with only three balls in play, any defect in one of them is in play on almost every shot.
Official UMB / CEB specifications
The international governing body for carom is the UMB, with the CEB governing Europe. Their equipment rules define the ball tightly:
- Diameter: 61.5 mm, with a small manufacturing tolerance (on the order of ±0.1 mm). Some older references and national bodies cite a 61-61.5 mm window; 61.5 mm is the modern standard.
- Weight: approximately 205-220 g per ball. The critical rule is not the absolute figure but the match: all three balls in a set must be weight-matched closely (typically within about 2 g of each other).
- Roundness and balance: the ball must be a true sphere with an even mass distribution, so it rolls without wobble and rebounds predictably regardless of which point of contact strikes the cushion.
The matched weight requirement is the one beginners overlook. If your red ball is heavier than your cue ball, energy transfer on the first hit shifts, the speed you "feel" stops matching the speed the ball actually carries to the rail, and every learned cushion line drifts. A properly matched set removes that variable entirely.
Spec comparison: carom vs pool vs snooker
| Property | Carom (three-cushion) | Pool (American) | Snooker |
|---|---|---|---|
| Diameter | 61.5 mm | 57.15 mm (2¼ in) | 52.5 mm (some sets 52.4 mm) |
| Weight (per ball) | ~205-220 g | ~156-170 g | ~142 g |
| Balls in play | 3 (white, yellow, red) | 16 (cue + 15 object) | 22 (cue + 15 red + 6 colours) |
| Pockets | None | 6 | 6 |
| Typical material | Phenolic resin | Phenolic resin | Phenolic resin |
The headline number is diameter: a carom ball is about 4.4 mm wider than a pool ball and 9 mm wider than a snooker ball. Combined with its higher mass, that is what gives three-cushion its distinctive, energy-rich rebounds across two, three, or more rails.
Material history: ivory, crystalate, phenolic resin
Through the 19th century the finest balls were turned from elephant ivory. Ivory was dense and hard but deeply flawed: it was inconsistent (no two tusks were alike), it absorbed moisture and warped, it discolored, and it cracked. The hunt for a substitute famously spurred the invention of early plastics — celluloid, and then materials like crystalate (a casein/composite ball widely used in the early 20th century, particularly for snooker).
The decisive leap was phenolic resin — a hard thermoset plastic. The Belgian manufacturer Saluc, under the Aramith brand, became the de facto standard for cast phenolic balls used across carom, pool, and snooker worldwide. Phenolic resin is what made the modern, repeatable game possible, and it is why "Aramith" is shorthand for tournament-grade balls in pro halls.
Why density and elasticity decide your cushion lines
Three-cushion is a game of systems: players count diamonds (the inlaid markers on the rails) and apply arithmetic — the classic corner-five / diamond system and its many variants — to predict where the cue ball will land after bouncing off two or three cushions. Those systems only work if the ball behaves the same way every single time. The physics that govern that consistency are:
- Coefficient of restitution (elasticity): how much speed the ball keeps after a collision. Phenolic resin is highly elastic and uniform, so a ball entering the cushion at a known speed and angle leaves it at a predictable speed and angle. A soft or porous ball deadens unpredictably.
- Density and hardness: a dense, hard ball deforms minimally on impact, transfers energy cleanly, and resists picking up dirt that would change its friction. This stabilizes both ball-to-ball throw and ball-to-cushion rebound.
- Roundness: any out-of-round ball changes its contact point shot to shot, scattering your rebound angles.
Put bluntly: a diamond system is a calibrated instrument, and the ball is part of the instrument. Play your learned lines with a warped budget ball and the geometry is right but the equipment lies — you will "miss by a ball" repeatedly and wrongly blame your stroke. Quality balls are what let you trust the count.
Aramith grades for carom
Aramith offers several phenolic carom grades. Honest differences come down to consistency of the phenolic cast, hardness, polish, and how long they hold their finish under heavy play:
- Aramith Tournament: the workhorse competition set for most clubs and serious amateurs. True 61.5 mm, matched weights, excellent rebound. For the vast majority of players this is all the ball you will ever need.
- Aramith Super Pro / Pro Cup style: top-tier sets, often with engineered markings (logos or the visible spot/positioning marks) that help referees and players read cue-ball spin on broadcast and in elite play. Tightest tolerances and the most uniform phenolic.
- Aramith Black series (Black Pearl / black-and-white aesthetic sets): premium phenolic with a distinctive dark finish, marketed for both performance and looks. Performance is in the tournament tier; the differentiator is appearance and a high-end polish.
Below these sit entry "club" or generic phenolic sets, and beneath those, polyester/acrylic balls. The acrylic sets are fine for occasional casual knock-about, but they are softer, less perfectly round, and far more prone to warping with heat — exactly the wrong material if you are trying to learn systems.
Cleaning, storage, and avoiding warp
Phenolic balls are durable, not indestructible. A clean, true ball rolls and rebounds as designed; a grimy one picks up chalk and skin oils that change friction and throw.
- Wipe after every session with a clean micro-fibre cloth to lift chalk and oils before they bake onto the surface.
- Use a proper ball cleaner/restorer (Aramith and others make dedicated products) periodically. Avoid harsh household solvents and abrasives, which can dull or micro-scratch the polish.
- Never use a ball-polishing machine aggressively on phenolic beyond what the cleaner instructions allow; over-buffing generates heat.
- Keep balls away from heat. Phenolic is a thermoset and resists heat far better than acrylic, but no plastic ball loves a hot car trunk, a sunny windowsill, or a radiator. Heat is the number-one cause of subtle warping and crazing.
- Store in a padded case or the original tray at stable room temperature, not loose in a bag where they clack and chip.
How to spot a worn or chipped ball
Even good balls eventually age. Retire or replace a ball when you see any of these:
- Chips or flat spots — even a tiny chip ruins roundness and makes the ball jump or veer on slow rolls.
- Visible scuffing or "frosting" that no longer cleans off — the polish is gone and friction has changed.
- Crazing — fine spider-web cracks in the surface, usually a sign of heat exposure or age.
- The roll-and-spin test: spin the ball in place on a flat slate; a true ball spins smoothly and dies in place, while a warped or unbalanced ball wobbles or walks. Rolling it slowly across the table should follow a straight line with no veer.
- Mismatched feel — if one ball consistently "feels" different in pace, weigh the set; an off-weight or worn ball should be pulled.
Recommended sets by budget
- Casual / beginner: an entry-level phenolic or quality acrylic carom set. Fine for learning to hit three balls cleanly. Don't build your system memory around it long-term.
- Serious amateur / club (best value): an Aramith Tournament carom set. This is the honest recommendation for most readers — true spec, matched weights, will outlast many cheaper sets, and lets you trust your diamond lines.
- Competition / elite: an Aramith Super Pro / Pro-grade set with positioning marks, for the tightest tolerances and the easiest spin-reading.
- Premium / showpiece: an Aramith Black-series set if you want top-tier performance with a distinctive look.
Two practical notes: always buy a matched three-ball carom set rather than mixing singles, so weights and finish are guaranteed to agree; and confirm the diameter is genuinely 61.5 mm, since some listings quietly ship undersized "carom-style" balls.
Key takeaways
- Carom balls are 61.5 mm and ~205-220 g — bigger and heavier than the 57.15 mm pool ball and the 52.5 mm snooker ball.
- A set is three balls: white, yellow (often dotted) and red, weight-matched to within a couple of grams.
- Phenolic resin (Aramith) replaced ivory and crystalate because it is dense, hard, and elastic — and that consistency is what makes diamond-system calculations reliable.
- Aramith Tournament is the value sweet spot; Super Pro and Black series sit above it for tolerances and looks.
- Wipe after play, clean with proper products, keep balls away from heat, and retire any ball that is chipped, crazed, or wobbles on the spin test.