Short Answer
To identify a fake IW371479, check four things in order: the subdial count and position, the caseback reference engraving, the case diameter, and the finish of the movement. A genuine IW371479 is a stainless steel IWC Portugieser Chronograph with a 40.9 mm case, two subdials, no date window, and a Valjoux 7750 based calibre. A counterfeit fails at least one of those four checks.
What the IW371479 Should Be
The 3714 family is a two register chronograph. Running seconds sit at 6 o'clock, elapsed chronograph minutes sit at 12 o'clock, and the dial carries applied Arabic numerals with leaf shaped hands. The case is stainless steel, roughly 40.9 mm wide without the crown, and the crystal is sapphire with a light anti reflective coating. There is no date aperture anywhere on the dial. The reference number 371479 belongs on the caseback, not on the dial.
Tools Worth Having
- A 10x loupe for dial printing and hands
- Digital calipers for case and lug measurements
- A small scale for weight comparison
- Bright, angled light with no window glare
How to Check a Suspect Watch
- Measure the case diameter across the bezel with the crown excluded, then compare the result to 40.9 mm.
- Count the subdials. Anything other than two, at 12 and 6, points to a different reference or a counterfeit built on a stock three register layout.
- Scan the dial for a date window. The 3714 family has none, so any aperture at 3 or between 4 and 5 is a mismatch.
- Inspect the hands under a loupe. Genuine leaf hands have a crisp central ridge and polished bevels that stay sharp to the tip, while replica hands look flat and thicker.
- Read every engraving on the caseback, including the reference number, case number, material mark, and water resistance rating.
- Check the dial printing with a magnifier. The IWC and Schaffhausen text should be sharp and spaced evenly, with no bleeding into the lacquer.
- Look at the movement through the display back if the watch has one. Look for perlage, blued screws, and a rotor engraving that matches IWC style rather than generic Asian 7750 decoration.
- Time the chronograph for one minute, stop it, and reset. The minute counter at 12 should advance in one minute jumps and snap back to zero without drifting.
- Press each pusher. Proper pushers move with light resistance and return cleanly, while gritty or loose pushers suggest a cheap movement underneath.
Details That Give Fakes Away
- Subdial spacing that is too wide or too narrow, which pushes the register edges away from the minute track.
- Caseback fonts that are too bold, too rounded, or unevenly stamped, with the reference number cut into the wrong spot.
- A case that measures 42 mm or more, borrowed from another model and sold as a 371479.
- Rotor engraving done with a laser instead of a deep stamp, which leaves a shallow, flat impression.
- A crown and pushers that sit proud of the case or wobble when pressed.
Buying a Replica of This Reference
A replica IW371479 should be judged on its own construction, not on how closely it mimics a real one. Ask which movement is inside, confirm that both subdials actually work, and check that the chronograph resets to zero on every push. A replica with a working minute counter and a decorated automatic movement costs more than one with a glued on subdial and a quartz module, and that difference shows on the wrist. Never sell or present a replica as a genuine IWC. If you plan to resell later, keep the original photos and the seller description on file.