A fake IW371613 is a counterfeit copy of an IWC Portugieser Chronograph, and the fastest way to expose one is to verify the reference number against IWC's own records, then compare the dial layout, subdial function, caseback engraving, and movement. Counterfeits rarely get all four right at the same time, so a single mismatch is usually enough to walk away.
What the IW371613 reference should be
IWC reference numbers are not random. The digits identify the family, the case material, the dial variant, and often the strap or bracelet the watch left the factory with. Before you judge any watch, confirm what the IW371613 is supposed to be: case size, dial color, hands, and the exact calibre used in that generation. IWC's official product archive and an authorized dealer are the only sources worth trusting for this. A seller who cannot state the reference correctly in the listing is already a red flag.
Why this reference gets copied
The Portugieser Chronograph is a simple, elegant design with a clean dial. That simplicity is exactly what makes it easy to fake. There are no complex complications to reproduce, no sapphire caseback details that demand precision, and the overall look reads the same from two feet away. Because of that, the difference between a real watch and a fake IW371613 shows up in small details rather than the overall shape.
Dial and hands: the quickest tells
Start here, because the dial is the part counterfeiters invest in least.
- Subdial function. On a genuine chronograph, the subdials actually track elapsed time. On many fakes, one subdial is decorative, runs on a quartz module, or jumps instead of sweeping. Ask the seller for a video of the chronograph starting, running, and resetting to zero.
- Printing. Look at the brand text, the numerals, and the railway track. Genuine printing is crisp with uniform stroke width. Fakes show blurry edges, uneven spacing, and font shapes that are slightly too wide or too narrow.
- Subdial spacing. Subdial positions are dictated by the movement underneath. When a counterfeit uses a different movement, the subdials sit too close together, too far apart, or too high on the dial.
- Hands. Genuine hands are cut and finished with sharp edges and consistent lume. Fakes often show rough polishing, mismatched lume color, or a seconds hand that sits at the wrong height above the dial.
- Date window. Check the position, the cut of the aperture, and whether the date font matches what the reference should have.
Case, crown, and pushers
Case finishing is where a fake IW371613 usually gives itself away under good light. Run a fingernail along the edges of the lugs. Genuine cases have a defined transition between brushed and polished surfaces. Counterfeit cases often feel rounded, with polishing that bleeds over into areas that should be brushed. Check the crown and pushers too: they should seat squarely, screw down smoothly, and return with a firm click. Loose or wobbly pushers point to a cheap movement inside.
Caseback engraving and reference number
Turn the watch over and read the engraving with a loupe or a phone camera zoom.
- The reference number should match the listing and the paperwork.
- Lettering should be sharp, evenly spaced, and cut into the metal rather than stamped on the surface.
- Serial numbers on fakes are frequently repeated across batches, so search the number before you buy.
- Sapphire casebacks, when present, should show a movement finished to a standard you would expect at this price point.
Movement: where most counterfeits fail
The current Portugieser Chronograph generation uses an in-house IWC chronograph calibre, while older references used a modified base chronograph movement. Confirm which calibre belongs to the exact reference you are looking at before you judge anything. A watchmaker can open the caseback in minutes and tell you whether the movement matches, whether the rotor engraving is correct, and whether the finish is machine-applied or hand-finished. Never open a case yourself, and never buy a watch on the promise that the movement is correct.
Strap, buckle, and packaging
Straps and boxes are the easiest parts to swap, so treat them as supporting evidence rather than proof. Look at the stitching density on the leather, the shape of the buckle, and the font on the packaging. A genuine box with the wrong watch inside is common in the counterfeit market.
Paperwork, price, and provenance
If the price is far below the market for a comparable example, the reason is almost never a bargain. Ask for the original invoice, the service history, and the name of the dealer. Then call that dealer to confirm. Counterfeit watches are subject to seizure at the border in the United States, and buying one carries real legal and financial risk, so a saved dollar is not worth the exposure.
What to do if you suspect a fake
- Stop the transaction and do not send payment.
- Have an independent watchmaker or an authorized IWC service center inspect the watch.
- Document everything: listing photos, messages, and the seller's details.
- Report the listing to the platform and, where relevant, to the brand and customs authorities.
The same checks apply to any luxury chronograph you buy secondhand. Verify the reference, confirm the movement, and get the watch inspected before money changes hands. That process takes an afternoon and protects the whole purchase.