A fake IW371640 is a counterfeit copy of an IWC Portugieser Chronograph, and the quickest way to judge one is to compare the caseback engraving and the chronograph movement against a genuine reference. Genuine IWC chronographs from the IW3716 block use an in-house caliber with a signed and decorated rotor, plus caseback markings cut deep and clean. Most fakes fail on the movement first and the dial second.
This guide explains what the reference number means, which details counterfeiters usually miss, and how to check a watch before any money changes hands.
What the IW371640 Reference Tells You
References starting with IW3716 belong to the IWC Portugieser Chronograph family. The line is built around a bicompax layout with two subdials, a slim bezel, applied numerals, and an in-house chronograph caliber in current production. That matters for authentication, because a counterfeit has to imitate a specific movement architecture and not just a dial design.
Ask the seller for the full reference as it appears on the caseback, not as it appears in the listing title. Listings that shorten or blur the reference number usually have something to hide.
How to Spot a Fake IW371640
Work through these checks in order. The movement and the caseback solve most cases on their own.
- Caseback engraving. Look for even depth, sharp letter edges, and consistent spacing between the reference, the serial, and the brand markings. Lasered or stamped fakes look shallow, fuzzy at the edges, or slightly different in font weight from one line to the next.
- Movement. A genuine IWC chronograph caliber shows Geneva stripes or circular graining, blued or polished screws, and a rotor engraved with the brand and caliber number. Unmarked rotors, printed decals, or a generic third-party chronograph module are the standard tells.
- Subdial placement. The counters must sit on the crown axis with even spacing. Many fakes are a millimeter or two off because the movement inside is a different size than the original.
- Dial furniture. Applied numerals on a genuine watch sit proud of the dial with polished bevels and cast shadows. Fake numerals are often flat, glued, or slightly misaligned.
- Hands and printing. Check that the chronograph hand resets exactly to twelve and that the dial text is crisp under magnification.
- Case finishing. Brushed and polished surfaces should meet on a clean line. Polishing compound left in the crevices and mismatched lug brushing are common on copies.
- Crown and pushers. Threading should feel smooth, and each pusher should give a firm, defined click instead of a mushy or gritty press.
- Crystal. Sapphire feels cold, resists scratching, and reflects light with a sharp edge. Mineral glass on cheaper copies picks up fine scratches and reflects differently.
Fake, Replica, and Homage: What the Words Mean
- Counterfeit or fake. A watch made to pass as the genuine article, carrying the brand name and logo it has no right to.
- Replica. Trade shorthand for the same thing, usually sold openly as a copy rather than as the real watch.
- Homage. An unbranded watch that borrows a general design language without copying the name or logo.
In the United States and most other markets, selling counterfeit branded goods is illegal, and customs authorities can seize shipments. That is a buying risk as much as a legal one, since a seized watch rarely comes back.
Price and Seller Signals
Price is the least reliable test on its own, but a steep discount on a Portugieser Chronograph is a strong warning sign. Treat anything far below the going pre-owned level as a fake until proven otherwise.
Seller behavior matters just as much:
- Refuses to send movement photos or a shot of the caseback with the serial visible.
- Pushes an untraceable payment method with no buyer protection.
- Uses photos that appear in other listings or on review sites.
- Cannot explain where the watch was purchased or serviced.
Box, Papers, and Service History
Boxes, booklets, and warranty cards are easy to reproduce, so they add confidence but prove nothing. A service invoice from an independent watchmaker, with a parts list that matches the caliber, is much harder to fake. If the seller will not let a watchmaker open the caseback before purchase, walk away.
What to Do If You Already Bought a Fake IW371640
- Stop wearing the watch and photograph everything: the listing, the messages, the packaging, and the watch itself.
- Contact the platform or seller in writing and request a return and refund.
- If payment went through a card or protected service, open a dispute while the window is still open.
- Report the listing to the marketplace and, in the US, to the relevant consumer protection or customs authority.
The safest habit is simple: verify the movement, verify the caseback, and verify the seller before you verify the price.