Short answer
A replica IW371613 is a counterfeit copy of the IWC Portugieser Chronograph. It is not an IWC watch, it does not come with IWC service or warranty, and it can be seized or refused entry in the US. If you are still comparing replicas, judge the watch on case finishing, subdial spacing, date magnification, movement behavior, and paperwork. Ignore '1:1' claims until those basics hold up.
What the IW371613 is
The IW371613 sits in the Portugieser Chronograph line. The real watch is a two-register chronograph with a 41 mm case, a 30-minute counter at 12 o'clock, small seconds at 6 o'clock, and a date window at 3. IWC fits it with an in-house automatic chronograph movement. The dial layout looks simple, which is exactly why copies are hard to get right. Any shift in the subdial spacing or date position shows up fast.
Why replicas vary so much
Most replica sellers use the same photos but ship different grades. One batch may have a decent case profile and a rough movement. The next may have a cleaner dial and a thick caseback. 'Swiss made' on a replica dial means nothing. The only useful comparison is the watch in front of you against known reference points. Price alone tells you little.
What I inspect first
- Case finishing: look for soft edges, uneven brushing, and polished bevels that do not line up.
- Subdial spacing: the 12 and 6 counters should sit on the vertical center line with even gaps.
- Date window: magnification, font, and alignment matter more than the cyclops shape.
- Movement behavior: start, stop, and reset the chronograph. The seconds hand should snap back to zero without wobble.
- Caseback and engraving: depth, font, and spacing are common weak points.
- Paperwork: a replica with 'certificates' is still a replica. Fake paperwork adds no authenticity.
Legal and practical risks
In the US, importing or selling counterfeit branded watches can lead to seizure, civil liability, and in some cases criminal exposure. A personal purchase does not give you a clean title, and resale can turn a quiet purchase into a legal problem. You also get no manufacturer service, no parts support, and no realistic resale value. If the watch fails, a local watchmaker may refuse to touch it or may not find parts.
A saner alternative
If you like the Portugieser look, compare it with legitimate chronographs from brands such as Seiko, Tissot, or Hamilton. You give up the IWC name, but you get a real warranty, service support, and a watch you can sell without hiding the listing. That is the trade I would make every time.