A fake IW371431 is a counterfeit of the IWC Portugieser Chronograph, a 40.9 mm steel watch with chronograph subdials at 12 and 6, no date window, and an IWC calibre 79350 inside. Most counterfeits fail on three points: the case measures 42 mm or more and sits thicker than 12.3 mm, the subdials sit in the wrong places or a date appears at 3 o'clock, and the movement shows an unmodified third-party chronograph instead of IWC finishing. Check those three first, then move to dial printing, hands, and engraving.
What are the exact specs of a genuine IW371431?
The reference identifies one dial and strap combination inside the IW3714 Portugieser Chronograph family, so the case and movement specs stay constant across the line. Expect a 40.9 mm stainless steel case, roughly 12.3 mm thick, sapphire crystal with anti-reflective coating, and water resistance rated to 3 bar. The dial carries applied indices, feuille leaf hands, and a printed minute track with no luminous material on most variants.
How do you tell a fake IW371431 at a glance?
- Dial layout. Real ones run a 30-minute counter at 12 and running seconds at 6. Anything at 9, or any date aperture, is wrong.
- Case size. Measure it. Fakes commonly land at 41.5 to 42.5 mm.
- Thickness. A 7750-based replica often runs 13.5 mm or more because the movement sits in a spacer.
- Hands. Genuine leaf hands are gold-plated, thin, and sharply pointed, with a polished bevel along the edge.
- Printing. The "IWC" and "SCHAFFHAUSEN" text is crisp, evenly spaced, and sits level with the subdial edges.
- Crown and pushers. The crown carries a sharp Probus Scafusia engraving. Fakes show a shallow or blurry stamp.
What should the movement look like?
The IWC calibre 79350 is a heavily reworked Valjoux 7750 with a 44-hour power reserve and a 28,800 vph beat rate. In watches with a display back, the rotor and bridges show Geneva stripes, circular graining, blued screws, and the IWC medallion. A bare, grey, undecorated chronograph module is the clearest sign of a counterfeit.
Where do high-end replicas get closest?
Top-tier replicas copy the case profile and dial layout well enough to pass at arm's length. They fall apart on the small parts: crown engraving depth, the polish on the bezel edge, the flatness of the sapphire, and the feel of the chronograph pushers. Genuine pushers have a short, crisp travel, while replica pushers feel spongy or grind at the end of the stroke.
How much should a genuine IW371431 cost?
A used IW3714 Portugieser Chronograph usually trades between about 5,000 and 8,500 US dollars depending on dial variant, box, and service history. Offers far below that range, especially from a private seller with no papers, point to a counterfeit or a stolen piece. Ask for a service invoice or an extract from the archives before you pay.
What about the box and papers?
Paperwork is easy to fake, so treat it as a secondary signal rather than proof. Compare the serial on the caseback with the warranty card, then verify the number with an IWC boutique or an authorized service center. A mismatched serial is a hard stop.
Sixty-second authentication checklist
- Measure the case: 40.9 mm, not 42.
- Confirm subdials at 12 and 6, and confirm there is no date.
- Read the dial printing under a loupe for sharp edges.
- Check crown engraving and pusher feel.
- Match the serial to the paperwork, then verify it.