A good replica of the IWC Portugieser Chronograph IW371655 gets four things right: a 41 mm case, roughly 13 mm thickness, sub-dials at 12 and 6, and a chronograph movement with a crisp reset. If a build misses any of those, it is not top tier, no matter how the listing photos look. Use the steps below in order and reject the watch at the first failure.

Prerequisites

  • Know the genuine specs: 41 mm stainless steel case, about 13 mm thick, leaf-shaped hands, applied markers, sapphire crystal with coating on both faces.
  • Set a budget before you message a seller. Top-tier builds sit well above entry-tier ones.
  • Confirm the seller accepts QC photos and has a stated return window.
  • Plan to have the watch checked on a timegrapher after delivery.

How to vet the watch, step by step

  1. Ask the seller to confirm in writing which factory produced the watch and which movement it carries.
  2. Request close-up photos of the dial, caseback, clasp, and both case flanks before payment.
  3. Measure the case across the widest point, crown excluded, and confirm 41.0 mm.
  4. Measure thickness from caseback to crystal and reject anything above 13.5 mm, which signals a cheap caseback and a thick movement spacer.
  5. Check the sub-dial centers. The 30-minute counter sits at 12 and running seconds at 6, both aligned on the vertical center line.
  6. Inspect the printing under magnification: the brand line and "SCHAFFHAUSEN" should be crisp, evenly spaced, and free of bleed.
  7. Look at the hands. Leaf-shaped hands should reach the minute track without touching it, and the chronograph hand should rest exactly at 12.
  8. Run the chronograph. Start, stop, and reset five times and confirm the hand snaps back to zero every time without drifting.
  9. Press the pushers. They should feel firm with a short throw, not mushy or grinding.
  10. Read the caseback engraving. Letters should be cut, not laser-dotted, and the reference line should match the genuine layout.
  11. Turn the watch over and listen. A rattling rotor or a loose automatic weight is a fail.
  12. Check the strap and buckle alignment, stitch density, and the tang or deployant fit against the case lugs.
  13. Place the watch on a timegrapher and accept only readings within about plus or minus 15 seconds per day in all positions.

Movement options you will see

Most replica IW371655 builds use one of three movements. The Asian 7750 derivative is the cheapest and the thickest, and it usually pushes the case past 14 mm. The cloned 69355 style movement copies the column-wheel layout and keeps the profile closer to the genuine watch, but quality varies by batch. A decorated 7750 with a modified rotor sits in the middle. Ask which one you are buying, then match the answer against the measured thickness.

Red flags

  • Stock catalogue photos instead of pictures of the actual watch.
  • No factory name, or a factory name that changes between messages.
  • A price far below the normal range for that factory.
  • Sub-dials that sit low or off-center, which means a movement spacer is doing the work.
  • A seller who refuses close-ups of the caseback or the clasp.

After delivery

Wind the watch 40 turns, set the time, and let it run for 24 hours before judging accuracy. Photograph the case under direct light to check for machining marks, then log the timegrapher numbers so you have a baseline for any warranty claim.