Quick answer
A fake IW371655 is a counterfeit of the IWC Portugieser Chronograph sold under that reference number. Copies exist, and the ones easiest to catch are the ones that get the chronograph layout wrong. The dial logo is the least useful test. Run the chronograph, check which subdial counts minutes, read the caseback engraving, and compare the whole watch against the specification IWC publishes for IW371655. If any of those checks fails, walk away.
Know the real reference first
The IW3716 family is the current Portugieser Chronograph: a stainless steel case around 41 mm, two subdials at 12 and 6, a date at 3, applied Arabic numerals, and leaf-shaped hands. The version you are buying may be steel on leather, steel on bracelet, or a precious metal case, so pull the exact variant before you judge anything. Counterfeiters copy the popular dial colors first and the rare ones poorly.
How to check an IW371655
- Write down the full specification for IW371655 from the manufacturer: case size, caliber number, power reserve, water resistance, and dial variant.
- Start the chronograph and watch the subdial at 12. On a genuine Portugieser Chronograph that register counts elapsed minutes. On many fakes it is a 24-hour indicator that never moves.
- Confirm the subdial at 6 keeps running seconds while the chronograph is engaged. If it stops when you press start, you are looking at a quartz module or a mismatched movement.
- Stop and reset. The minute counter has to snap back to zero in one motion. Hesitation, overshoot, or a hand that lands off center points to a low-grade chronograph movement.
- Check the date window. The aperture should be cut clean with sharp corners, and the date disc should sit level with the dial.
- Inspect the dial print under a 10x loupe. Look at the brand logo, the SCHAFFHAUSEN line, and the numerals. Genuine print has crisp edges and even depth. Fakes show fuzz, uneven spacing, or lettering that is slightly too heavy.
- Examine the hands. The leaf hands should taper to a point, and the subdial hands should reach the inner track without overhanging it.
- Turn the watch over. Genuine caseback engraving is cut with consistent stroke width, and the reference and serial numbers match the documentation.
- Weigh it in your hand and work the crown and pushers. A steel Portugieser Chronograph has real heft, and the pushers have a short, firm throw.
- Ask for a movement photograph, service records, and the original purchase receipt. A seller who refuses all three is describing a fake, whatever the listing claims.
Where copies give themselves away
- Subdial function that does not match the reference layout.
- Case thickness that runs over the genuine measurement to hide a thicker movement.
- Sapphire crystal with a heavy blue tint instead of a faint anti-reflective sheen.
- Strap stitching that is machine straight and hardware that is stamped, not milled.
- Engraving that is laser burned, grey, and shallow rather than cut into the metal.
Movement and finishing
Open the caseback only if you own the watch or the seller agrees in writing. Look at the rotor engraving, the balance bridge, and the perlage. Genuine IWC finishing is even across every visible surface, including the parts hidden under the rotor. Fakes finish the rotor and leave the rest rough. Check the caliber number printed on the movement against the caliber IWC declares for IW371655, and confirm the beat rate rather than trusting a sticker.
Caseback, papers, and serial numbers
Serial numbers sit between the lugs or on the outer caseback, depending on production year. Ask the seller for a clear macro photograph of both the reference and the serial, then compare them with the warranty card and the box label. Numbers that are hand punched, uneven, or missing the correct spacing are a counterfeit signature. A box and papers set can be bought separately online, so treat paperwork as supporting evidence, not proof.
If you already bought a fake
- Photograph the watch, the listing, the payment record, and every message with the seller.
- Stop wearing it and stop any resale listing, since selling a counterfeit as genuine is a separate legal problem.
- File a dispute with your payment provider or card issuer inside the stated window.
- Report the seller to the marketplace and to the brand's trademark team.
- If the amount is large, contact your local consumer protection office or customs authority for guidance.
If you are shopping for a disclosed replica instead of a counterfeit, the same checklist still applies. A seller who hides the movement, the factory, or the return terms is a seller you cannot hold to anything after the money leaves your account.