If you are trying to work out whether an "IW371752 fake" listing is genuine, the most dependable answer comes from an authorized IWC service centre inspection, because only there can the movement be opened, logged and matched against the brand's own production records. The four criteria used to rank the options below are movement verification, the value of the paperwork you end up holding, the time and cost involved, and how much protection the route gives you if the watch turns out to be counterfeit.
Authorized IWC Service Centre Inspection
IWC service centres and their authorized partners open the case, identify the calibre, and check whether the reference on the caseback corresponds to a configuration the brand actually built. That last point matters here, because a six-digit number in the IW3717xx block sits inside the Portugieser Chronograph family, and the definitive list of what exists lives in the manufacturer's own catalogue and archive. Replica listings often borrow a real reference to look credible, so the number by itself proves nothing.
Pros
- Movement identification is handled by people who work on this calibre family every day.
- You receive a written service estimate that doubles as documentation for insurance or a later sale.
- Non-original parts, refinished dials and re-cased movements get flagged rather than missed.
Cons
- You may be asked to show provenance or proof of ownership before the watch is accepted.
- Turnaround is measured in weeks.
- A full service quote on a counterfeit is money spent on a watch you will likely never wear.
Best for: a watch you already own, or one you are about to pay real money for, where a written verdict is worth the wait.
Independent Watchmaker Appraisal
A good independent watchmaker can do most of the same work at a lower price and far faster. Ask for the caseback to be opened, the calibre photographed, and the balance, column wheel and rotor markings compared against reference images. On a genuine Portugieser Chronograph in the current generation you would expect an in-house calibre 69355, a column-wheel chronograph layout and roughly 46 hours of power reserve; earlier 3714-generation watches used a 79350 base derived from the Valjoux 7750. Counterfeits in this segment usually run a generic Chinese automatic or, at the cheap end, a quartz module hidden behind a decorated rotor.
Pros
- Same day or next day turnaround in most cities.
- Cheaper than a manufacturer service intake.
- Useful for a pre-purchase opinion when the seller will not meet at a boutique.
Cons
- Quality of the verdict depends entirely on the individual watchmaker.
- Not an official record, so it carries less weight with insurers and future buyers.
- Some shops will not open a watch they did not sell.
Best for: a fast second opinion before you commit, or a watch with no service history and no box or papers.
Certified Pre-Owned and Authorized Dealer Purchase
The surest way to never face the IW371752 fake question is to buy through a channel that has already answered it. Authorized dealers and manufacturer-backed certified pre-owned programmes inspect, service and guarantee the watch before it reaches you, and they hand over the reference, the warranty and the service record in one package. That combination is what a private listing on a classifieds board almost never provides.
Pros
- Authenticity is verified by the seller before the sale, not after.
- Warranty coverage and a documented service history.
- Return rights if the watch does not match the description.
Cons
- You pay a premium over a private sale.
- Availability of one exact reference and dial variant can be thin.
- Waiting lists are common on popular configurations.
Best for: anyone buying their first serious watch, or anyone who wants the reference question closed permanently.
Checking the Watch Yourself: Reference, Dial and Caseback
Self-inspection will not confirm a movement, but it catches most bad listings in a few minutes. Work through these in order.
- Confirm the reference on the caseback matches the paperwork and the dial variant. IWC uses an IW prefix plus six digits, and mismatched references are the most common error in counterfeit listings.
- Look at the dial printing under a loupe. Genuine printing is crisp with clean edges; counterfeit text often shows uneven weight, filled-in letterforms or a blurry brand signature.
- Check subdial spacing and the date window position. Fakes usually get subdial placement close but not exact, and the date aperture edges look rough.
- Inspect the caseback engraving depth and the case finishing between the lugs. Laser etching on a fake sits shallow and looks flat under angled light.
- Examine the sapphire crystal for anti-reflective coating. A missing or purple-tinted coating on a watch of this class is a warning sign rather than a bargain.
Pros
- Free, immediate and requires no appointment.
- Filters obvious fakes before you travel to see a watch.
- Builds the eye you need for every future purchase.
Cons
- Cannot verify the movement, which is where the real money sits.
- High-quality counterfeits can pass a visual check.
- Judging from photos alone is unreliable.
Best for: a first pass on an online listing, never as the final word on a purchase.
What to Do With the Answer
If a service centre or a trusted watchmaker confirms the watch is counterfeit, stop spending on it. Counterfeit watches cannot be serviced with genuine parts, hold no resale value, and importing them into the United States is unlawful, with shipments subject to seizure and destruction. Your realistic options are to walk away, to seek a refund from the seller, or to report the listing to the platform and, where relevant, to the brand's anti-counterfeiting team.
If the watch turns out to be genuine, get the inspection report, the service record and the warranty card filed together. That paper trail is what converts a loose watch into a sellable one later. And if you simply want the look of the Portugieser Chronograph without the authentication risk, legitimate alternatives exist at every budget, from entry-level chronographs with sapphire crystals to well-regarded independent brands. None of them will carry the IW371752 reference, and that is exactly the point.