The best replica IW371652 is the build that reproduces the vertical two-subdial layout at 12 and 6, keeps the case close to 41 mm across and roughly 13 mm thick, and runs a chronograph that starts, stops, and snaps back to zero without a stutter. That is the top pick, and everything else on this reference, from the applied indices to the strap stitching, is a detail you can confirm in a photo before money changes hands. Judge any candidate against five criteria: case and crystal proportions, dial printing and subdial geometry, movement and pusher feel, strap and clasp finishing, and the quality of the pictures the seller will send you.

Why this reference is hard to copy well

The reference number places this watch in IWC's Portugieser Chronograph family, a line defined by a clean, wide dial and a stacked register layout. That layout is the problem for anyone building a copy. Most inexpensive chronograph movements put registers at 9, 12, and 6, so a factory that reuses one has to blank a register, relocate it, or print a dial that does not match the original spacing. The gap between the two subdials, the distance from each subdial to the center pinion, and the size of the date aperture are the three measurements that expose a lazy build fastest.

Criterion 1: case, crystal, and thickness

  • Pro: A well-made case in the 41 mm range looks correct on an average wrist and takes standard 20 mm straps.
  • Pro: Sapphire with a mild dome and an inner anti-reflective coating reads almost invisible at an angle.
  • Con: Thick cases are the most common failure. A chronograph movement plus a decorative rotor often pushes the watch past 14 mm, which changes the side profile.
  • Con: Polished lugs that are too sharp or too soft are hard to fix later. Case finishing cannot be upgraded after purchase.

Use case: if you wear the watch mostly under a cuff, thickness matters more than anything else on this list. Ask the seller for a caliper photo on the caseback before you commit.

Criterion 2: dial and subdial geometry

  • Pro: Good builds print the minute track with even spacing and crisp numerals, and the two registers sit on a true vertical axis.
  • Pro: Applied indices with polished edges catch light the way the original does.
  • Con: Repainted dials often show a halo around printed text or an off-center date window.
  • Con: Hand lengths are frequently wrong by a millimeter, which is small on paper and obvious on the wrist.

Use case: pick a dial variant you can verify against real photographs of the same reference. A blue or white sunburst finish hides small printing flaws better than a flat black dial.

Criterion 3: chronograph and movement feel

  • Pro: A correctly assembled chronograph module gives a firm pusher click and a clean reset to 12.
  • Pro: Quickset date and hand-winding that feels smooth point to a movement that was actually serviced before shipping.
  • Con: Cheap vertical-clutch conversions can drift, and the chrono seconds hand may not return exactly to zero.
  • Con: Any dealer who will not run the chronograph on video is a risk you do not need to take.

Use case: buy the version with the better movement even if the case is slightly less polished. A sticky reset ruins the watch in daily use.

Criterion 4: strap, clasp, and presentation

  • Pro: A leather strap with real stitching and a signed pin buckle completes the look for very little money.
  • Pro: Factory packaging photos give you a baseline for what the seller actually stocks.
  • Con: Stiff, shiny leather and a stamped buckle are the easiest tells to spot across a table.

Use case: budget for a replacement strap from day one. It is the cheapest upgrade that changes how the whole watch reads.

How to run a pre-shipment check

  1. Ask for a timestamped video with the chronograph running.
  2. Request a straight-on dial shot and a side profile shot on a flat surface.
  3. Compare subdial positions to reference photos, not to other replicas.
  4. Confirm the return window in writing before paying.

Legal and practical note

Replica watches are counterfeit goods. In the United States, trademark counterfeiting is illegal and shipments can be seized at the border, so you carry the risk of losing both the watch and your money. The IW371652 is a trademarked design, and no replica is a genuine IWC product or carries any manufacturer warranty or service support.

Bottom line

Rank candidates by case thickness first, dial geometry second, movement third, and strap last. The best replica IW371652 for most buyers is the thinnest, best-photographed build from a seller who answers questions with a camera in hand rather than a paragraph of marketing text.