The crown assembly is the top pick for a first check on any Ballon Bleu, genuine or not. Cartier builds that crown into a curved guard so it sits flush against the case band, then caps it with a blue cabochon. Four things decide the outcome in order: crown geometry, cabochon shape and color, dial texture, and engraving quality. A buyer who knows those four can sort most replicas from genuine watches in about a minute, without opening the case.
Check 1: Crown, Guard, and Cabochon
On a genuine Ballon Bleu the crown guard is not a separate piece bolted on. It flows out of the case band in one smooth curve, and the fluting on the crown runs fine and even. The cabochon on most references is a synthetic blue spinel, domed on top and flat underneath, set level with no visible glue line.
- Pros: fast, needs no tools, and works from sharp photos.
- Cons: some replicas copy the silhouette well and only fail on cabochon material.
Use it when: you are looking at listing photos and want a yes or no in seconds. Look for a cabochon that is too bright, too purple, flat instead of domed, oversized, or sitting proud of the crown. Glass and plastic read differently under light than a polished stone, and they scratch in a way spinel does not.
Check 2: Dial Guilloché and Roman Numerals
The dial carries a concentric guilloché texture. On a genuine dial the rings are cut to an even depth across the whole surface, and the light moves over them in a consistent wave as you tilt the watch. The Roman numerals should be crisp, evenly inked, and correctly spaced against the inner track. Several references also hide the word Cartier inside one of the numerals, so a missing secret signature on a model that should have one is a problem.
- Pros: dial work is expensive to copy, so weak guilloché is a common giveaway.
- Cons: dial layouts changed across sizes and years, so compare against the exact reference.
Use it when: the crown check is inconclusive. Printed numerals that look soft or thick, a date window that sits off-center, or rings that fade toward the edges all point the same direction.
Check 3: Case, Crystal, and Caseback Engravings
The sapphire crystal is domed and sits high, which is part of why the crown appears to float. The caseback carries the brand name, reference, serial, water resistance rating, and Swiss Made marking. Genuine engraving has depth and clean edges. Replica engraving tends to look shallow and lasered, with letters that are too wide or too uniform.
- Pros: engraving depth is hard to fake and easy to photograph with side light.
- Cons: older genuine watches can show worn or polished-down markings.
Use it when: you can ask the seller for a close macro shot of the caseback. Serial numbers should match the paperwork, and the reference should match the case size and dial layout.
Check 4: Movement and Winding Feel
Gold references often have an exhibition back, so the automatic movement is visible. Expect a signed rotor, Geneva stripes, and blued screws. Steel references usually have a solid back, which means you judge the movement by behavior instead. It should hack when you pull the crown, wind with light resistance, and sweep rather than tick.
- Pros: a quartz movement in a watch sold as automatic ends the discussion.
- Cons: you cannot inspect a movement through a solid caseback without a watchmaker.
Use it when: you have the watch in hand. A second hand that jumps once per second is the single clearest fail on an automatic reference.
Check 5: Bracelet, Clasp, and Weight
Steel bracelets alternate brushed and polished link faces, and the end links meet the case with no gaps. The clasp closes with a firm double-fold action and carries crisp engraving. A steel Ballon Bleu should feel dense on the wrist for its size.
- Pros: weight and clasp action are difficult to disguise in person.
- Cons: subjective, and a missing link or aftermarket strap changes the feel.
Use it when: you meet a seller face to face. Ask to hold it, then check for rattle in the bracelet and looseness where the end links meet the lugs.
Which Check to Use First
- Photos only: work the crown and cabochon, then the dial.
- In hand: add weight, clasp action, and the sweep of the seconds hand.
- Before paying a large sum: have a watchmaker open the case and confirm the movement.
No single check proves anything on its own. Two or three failures together do. If the cabochon looks flat, the guilloché fades at the edges, and the caseback engraving looks shallow, you already have your answer.