The short answer
A fake IW371490 is a counterfeit copy of the IWC Portugieser Chronograph, a two-register chronograph with a 40.9 mm steel case, a sapphire crystal and an automatic movement. No replica matches the real watch in every respect, and the good ones do not try to. They win on silhouette, dial printing and wrist presence, and they lose on case thickness, movement architecture and caseback finishing. Judge a replica on those four things before you judge anything else, and go in knowing you are buying an unlicensed copy with no warranty, no factory service and a genuine chance of seizure at the US border.
What to check, in order of importance
1. Case thickness and profile
The genuine 3714 family sits near 12.3 mm thick. Replicas built on a 7750-family chronograph movement often measure 13.5 to 14.5 mm because the movement stack is taller than the original. That extra millimeter changes how the watch sits under a cuff and how the lugs look from the side. Ask for a photo of the case on calipers, not a photo of the watch on a wrist. A 1 mm difference is hard to see on a padded cushion and easy to see on a measuring tool.
2. Subdial spacing and dial furniture
This is a two-register layout: chronograph minutes high, small seconds low. On cheaper replicas the subdial centers creep toward the middle of the dial, the printed rings read too thick, and the applied numerals show soft edges and uneven polishing. Compare the distance from the case center to each subdial center, not just the overall dial diameter. Also check the date aperture position and the font of the numerals if the reference you are studying carries a date.
3. Movement
Recent genuine production uses IWC calibre 69355, while older references used the 79240, itself a modified Valjoux 7750. Replicas run a 7750 clone or a modified automatic with decorative plates and fake rotor engraving. Ask for a photo with the caseback off. Rotor text, perlage and bridge shape are where most copies fall apart, and no amount of case finishing hides a wrong movement.
4. Crystal, crown and pushers
The genuine crystal is sapphire with anti-reflective coating on both faces and almost no color cast. Cheap replicas show a strong blue or purple tint when you tilt them toward a light. The crown should have crisp knurling, firm pusher action and no lateral play.
5. Caseback and engraving
Reference and serial engraving on a genuine case is cut deep with clean edges. Laser etching on replicas looks shallow and dotty under a loupe, and the letter spacing drifts on longer text strings.
Parameter bands worth measuring
- Case diameter: 40.9 mm genuine, replicas land between 40.5 and 41.5 mm
- Thickness: 12.3 mm genuine, 12.8 to 13.5 mm acceptable, 14 mm and up is a visible tell
- Lug width: 20 mm
- Water resistance: rated to 3 bar genuine, treat any replica as splash contact only
- Power reserve: roughly 40 to 46 hours
- Crystal: sapphire, coated, no visible color cast
Pitfalls to watch for
- Listings illustrated with photos of a genuine watch rather than the actual item
- Claims of a perfect copy with no macro photos, no caseback shot and no measurement proof
- Sellers who will not provide a timestamped photo or a short video of the running chronograph
- Payment methods with no recourse if the parcel is stopped or swapped
- Dial colors and hand finishes matched to the wrong reference number
- Assuming a local watchmaker will service it. Many refuse to work on counterfeits, and clone movement parts are not always available
The legal and practical position in the US
Importing counterfeit goods into the United States is prohibited, and customs officers can seize the parcel and destroy it. Trafficking in counterfeit goods carries criminal penalties under federal trademark law. Beyond the legal exposure, a replica carries no manufacturer warranty, gets no service from IWC, and has effectively no resale market. If what you want is a genuine Portugieser Chronograph, buy from an authorized dealer or a dealer with documented service history and a proper authentication trail.
FAQ
Is a fake IW371490 worth buying?
Only if you accept that it is a counterfeit with no warranty, no official service path and a real risk of seizure during import. It will not appreciate and it will not fool a watchmaker.
How do I spot a fake IW371490 quickly?
Start with thickness on calipers, then subdial spacing, then the movement. Those three checks catch most copies within a minute.
Will a replica hold value?
No. Replicas depreciate from the moment they ship and resale platforms generally refuse them.
Can a replica be serviced?
Some independent watchmakers will handle a clone chronograph movement, but many decline, and parts availability depends entirely on which clone is inside the case.