Short answer: a fake IW371432 gives itself away in three places. The caseback engraving and serial format are wrong, the caliber 79350 does not behave like a reworked 7750, and the dial printing around the twin subdials looks soft. If any one of those fails, treat the watch as counterfeit and walk.
What the Genuine Reference Should Be
Memorize the specs first. You cannot judge a watch against nothing.
- Case: stainless steel, 40.9 mm across, about 12.3 mm thick, water resistance 3 bar.
- Dial: silver-plated, two registers, chronograph minutes at 12 and running seconds at 6.
- Movement: IWC caliber 79350, built on a 7750 base and rebuilt with a different chronograph layout.
- Crystal: domed sapphire with anti-reflective coating on both faces.
- Strap: alligator leather with a steel pin buckle or deployant clasp.
Prerequisites
- A 10x jeweler loupe.
- Bright light that you can angle across the surface. A phone flashlight works.
- A photo of a known genuine IW371432 caseback for side-by-side comparison.
- Calipers, if you can borrow a pair.
Step-by-Step Checks
- Measure the case with calipers. Fakes often run 1 to 2 mm thicker than the 12.3 mm spec because a stock 7750 sits tall inside the case.
- Study the dial under the loupe. Genuine printing has crisp edges with no ink bleed. Fake printing looks soft and fuzzy at 10x.
- Check the subdial axis. The registers at 12 and 6 must sit on the vertical center line. A stock 7750 donor movement often leaves a ghost of a date aperture or shifts the registers off center.
- Run the chronograph five times. Pushers should feel firm with a defined click, and the center hand must snap back to zero with no hesitation.
- Inspect the hands. Leaf-shaped hands on the original are polished with beveled flanks. Fake hands are stamped and show a flat, dull edge.
- Tilt the watch under the light. Original sapphire coating shows a faint blue or purple tint at an angle. Cheap mineral glass throws a heavy rainbow flare.
- Examine the caseback with the loupe. Genuine text is cut into the metal with sharp interior corners. Laser-etched fakes look shallow and grainy.
- Compare the serial and reference numbers against your reference photo. Font weight, character height, and spacing all matter.
- Check the buckle. Engraved IWC lettering must match the caseback font. Stamped or ink-filled lettering is a red flag.
- Hold the watch. A steel case feels dense and cold at first touch. A plated brass fake feels light and warms up fast.
Movement Checks
Open the caseback only if you own the watch or have written permission from the seller. A genuine caliber 79350 shows even finishing on the bridges, an engraved rotor with clean lettering, and no tool marks. Fakes show rough milling, uneven polishing, and a rotor that spins with a tinny rattle when you shake the watch.
Price and Seller Signals
Pre-owned steel IW371432 examples commonly sell between $4,000 and $7,000 depending on condition, box, and papers. A price far under that range, a seller who refuses a video call, or a listing with dial photos only are warnings. Request the serial number, a movement photo, and a written return window before you send money.
Red Flags That End the Inspection
- A reference number that does not match the dial layout shown.
- Caseback screws with damaged slots, which suggests the watch has been opened by an amateur.
- A chronograph hand that stops short of zero or drifts after reset.
- An alligator strap with printed, not embossed, scale texture.
- No service history and a seller who cannot name the last watchmaker who touched it.
Run the checks in order and stop at the first failure. One confirmed flaw is enough to call an IW371432 counterfeit, and no later detail will undo it.