The short answer
A "v4" replica IW371747 is the fourth revision of one factory's copy of the IWC Portugieser chronograph in that reference. It is not a separate model. Version numbers are internal to the maker, so v4 means the case, dial, and movement finishing were reworked three times before this release. Treat the label as a claim to verify, not a grade. Two sellers can list "v4" and ship different watches, because no one enforces the numbering.
What to confirm before comparing units
- Genuine reference specs: case diameter, thickness, lug width, dial layout, and strap size. Pull them from IWC, not from a listing.
- The factory name, in writing, from the seller.
- What the price covers: watch head only, or head plus pictured strap, box, and papers.
How to check a v4 build, step by step
- Request dated QC photos of the exact unit, with the caseback and crown side included.
- Measure the case in those photos against a caliper shot. Diameter and thickness should track the genuine figures within a few tenths of a millimeter.
- Compare the dial print. On the 3717 layout, check sub-dial placement (running seconds at 6, chrono minutes at 12), the date aperture, and the weight and spacing of the applied numerals.
- Examine hand shape and finish. Leaf hands should taper cleanly, with a polished bevel that runs the full length.
- Inspect caseback engraving depth and font. Shallow laser etching is the common tell on earlier versions.
- Ask which movement is inside and whether the chronograph uses a modular or integrated layout. Confirm the sub-dial hand returns to zero on every reset.
- Request a short video: start, stop, and reset the chronograph twice, then set the time and date. A slow reset or a date disc that hangs is grounds to reject the unit.
Water resistance and honest limits
Replica cases seldom carry a tested rating. A listing that says 30 m means splash resistance at best, and only once the caseback gasket sits clean and greased. Keep it out of the pool. Have a local watchmaker pressure test it before you trust it near water, and treat that test as the first real service.
Where v4 builds still fall short
- Crystal clarity and anti-reflective coating on both faces.
- Strap leather, which often trails the hardware.
- Movement finishing under a display back, where the price gap shows.
- Unit-to-unit consistency. v4 describes the design, not each individual watch.
Ownership notes
Budget for a service within the first two years, since the chronograph module carries the wear. Wind it at the same time each day, keep it off the crown when setting the date, and store it away from magnets. If the watch arrives with a stiff pusher or a misaligned sub-dial hand, raise it with the seller before you wear it, because the QC window closes fast.