A fake IW371772 is a counterfeit version of the IWC Portugieser Chronograph, and the fastest way to screen one is to verify the reference number before you study the dial. Confirm that the number was actually issued by IWC in that case size, metal, and dial color. Counterfeit sellers sometimes attach a plausible looking reference to a watch that never existed in that combination, so a number that does not check out ends the conversation. If the reference is valid, the next steps are printing quality, case finishing, movement behavior, and paperwork.
Why this reference attracts counterfeits
The Portugieser Chronograph is a plain watch on paper: two subdials, slim leaf hands, a printed minute track, and a thin bezel. That simplicity works in the seller's favor in photos, because there is no complex dial furniture to expose a copy. It works against the seller in the hand, because a minimal dial has nowhere to hide sloppy printing, and the chronograph function is hard to fake smoothly.
Step 1: verify the reference first
- Look the number up on IWC's own catalog or with an authorized dealer, not on a marketplace listing.
- Match the caseback engraving to the dial version: metal, case size, and dial color should agree.
- Watch for numbers borrowed from a different model line or a case size the reference was never made in.
Step 2: dial and printing checks
- Subdials sit at 12 and 6, recessed with a crisp step between the dial and the counter surface.
- The brand name and city line are sharp and evenly spaced, with no fuzzy or doubled edges under magnification.
- Applied indices are polished, seated flat, and reflect light on one consistent plane.
- The date aperture has straight edges, and the date font matches IWC's typeface rather than a generic office font.
Step 3: case, crystal, and crown
Genuine case finishing alternates brushed and polished surfaces with a defined line between them, and the lugs hold a strap flush against the case. The sapphire crystal has a slight dome with an anti reflective coating that shifts color subtly at an angle. Copies often look flat, or the coating throws a strong blue or purple tint. Threading on the crown should feel smooth and take a clean half turn before it seats.
Step 4: movement and caseback
Depending on the production year, the genuine watch runs an in-house 69355 chronograph calibre or the older 79350 base derived from the Valjoux 7750. Through a display back you see Geneva stripes, blued screws, and rotor engraving with clean edges. Counterfeits use stock chronograph movements with shallow rotor engraving, and the pushers feel gritty. Start the chronograph and watch the seconds hand: a real column wheel or cam setup sweeps in a steady arc instead of stuttering at the start.
Step 5: price, box, and papers
- Used prices for a given year and condition sit in a fairly narrow band. A price far under that band is the single strongest warning sign.
- Replica packaging often includes a box, warranty card, and manual that look close until you compare print weight, font spacing, and paper stock.
- Caseback serial numbers should match the paperwork. Any mismatch means walk away.
If you already bought one
- Take it to an independent watchmaker and have the case opened for a movement inspection.
- Request a verification or service quote from IWC so you have a written opinion.
- If you paid by card, open a dispute with your issuer and keep the listing and messages as evidence.
- Report the seller to the platform and to the brand's anti counterfeiting contact.
Bottom line
The reference number is the gate. Once a fake IW371772 clears that check, dial printing and chronograph feel decide the rest, because a minimal dial and a mechanical chronograph are the two things replicas get wrong most often. Buy from a seller who offers an inspection period, and budget for a movement service as part of the purchase.