The Fifty Fathoms Bathyscaphe Chronographe Flyback, reference 5200, is one of the most copied Blancpain models on the market. Fakes range from cheap quartz lookalikes to four-hundred-dollar automatics that get the silhouette right and the movement wrong. Four checkpoints will separate them in under a minute.

What the 5200 Is Supposed to Be

Blancpain revived the Bathyscaphe name in 2013 and added the flyback chronograph a year later. The modern 5200 runs a 43.6mm case, 300m of water resistance, and the in-house Calibre F385. That movement is a column-wheel, vertical-clutch flyback chronograph beating at 36,000 vibrations per hour, fitted with a silicon balance spring and roughly 50 hours of reserve. Dials have shipped in sunburst grey, blue, and black. The bezel insert is ceramic, and some versions use a Liquidmetal scale.

A genuine example sits in five-figure territory. That gap is exactly why the replica trade targets it.

The Four Checks That Do the Work

1. Flyback behavior

Flyback means you can restart the chronograph with a single push while it is still running. On the real 5200, the lower pusher resets the hands to zero and immediately restarts the timing in one motion. Most replicas fail this. The pusher either does nothing, stops the watch, or forces you to press twice. If the chronograph halts when you press the pusher at four o'clock, you are looking at a standard chronograph, not an F385.

2. The date aperture

The genuine date sits at 4:30, small and unobtrusive, with crisp printing and a wheel color matched to the dial. Replicas often use a generic date wheel with the wrong font, or a window set slightly off axis. Study the numerals one and seven. Font mismatches show up there first.

3. Subdial spacing

The 5200 places running seconds at nine and a 30-minute counter at three. Many replicas build on a modified third-party base with an added module, which pushes the subdials inward and adds thickness at the wrist. If the dial feels crowded or the case sits noticeably taller than the reference, that is a tell.

4. Caseback and rotor

The 5200 has a sapphire display back. The F385 shows Geneva stripes, blued screws, and a rotor engraved with the Blancpain wordmark and caliber number. Replica movements usually show shallow engraving, a plain rotor, and a balance wheel running at the wrong beat. Listen closely: five hertz has a higher pitch than the more common four hertz. On a quiet room, the difference is audible.

Case, Bezel, and Finish

Turn the bezel. A genuine Bathyscaphe clicks in even, defined steps with no back play. Replicas often feel gritty or loose. Case brushing on the real watch is fine and directional, while replica brushing is coarser and less consistent. The crown should be signed and screw down to a firm stop with correct thread pitch.

Lume is another giveaway. Genuine watches use Super-LumiNova applied at an even thickness, and the hands, markers, and bezel pip all glow the same color and intensity. Replicas frequently have mismatched lume between dial and bezel, or lume that fades within minutes.

Strap and Packaging

The Bathyscaphe ships on sailcloth or a NATO strap. Stitching on the genuine sailcloth is tight and even. Replicas use bonded leather with a printed texture that looks right in photos and wrong in hand. Boxes and papers matter too. Most replicas arrive in generic packaging, and the warranty card serial will not match the caseback.

What Replicas Get Right, and Why It Still Matters

A good replica captures the silhouette, the dial layout, and the wrist presence. From across a table it reads as a Bathyscaphe. Up close, it does not hold. Past the ethics, there is the practical side: no parts support, no service network, water resistance advertised at 300m but rarely tested past a sink, and a movement that may not survive a solid knock. If you own a genuine 5200, keep the service papers. If you are buying used, work with a seller who will open the caseback on camera.

Quick Checklist

• Press the pusher at four o'clock while the chronograph runs. It should reset and restart in one motion.
• Check date position and numeral font at 4:30.
• Listen to the beat. Five hertz, not four.
• Inspect the display back for Geneva stripes and a signed rotor.
• Turn the bezel and feel for even clicks with no slop.
• Compare lume color between the dial and the bezel pip.
• Match the caseback serial to the warranty card.

Replicas keep improving, and the 5200 is a frequent target because the design is clean and easy to copy. The movement is the hardest part to fake, so that is where the inspection should start.