Top pick: the best replica IW371620 is a top-tier build that holds the reference's 41 mm case, keeps thickness near 13 mm, uses 20 mm lugs, runs a slimmed automatic chronograph with clean pusher action, and prints the twin-register dial with level text and correctly shaped leaf hands. This guide ranks builds on four criteria: case geometry, movement behavior, dial and hand execution, and case finishing with strap and buckle. A build that passes all four wears convincingly. A build that fails one is obvious within a day of ownership.

Case Geometry: 41 mm Wide, About 13 mm Thick, 20 mm Lugs

The Portugieser Chronograph reference is a 41 mm watch with roughly 13 mm of thickness and 20 mm between the lugs. Replica cases in the top tier copy those figures closely, because the same CNC blanks are used across several 41 mm chronograph models and then hand finished. Thickness is where budget builds fall apart. A standard Asia 7750 under a decorative plate often pushes a case to 14 mm or 15 mm, and that extra millimeter changes how the watch sits under a cuff and how it reads in a profile photo.

Pros

  • Correct 41 mm and 20 mm numbers keep factory straps, aftermarket alligator, and steel bracelets interchangeable.
  • A thinner case sits flat on the wrist and hides less well under a shirt sleeve.
  • Lug curves that match the reference mean the watch does not overhang a 6.5 inch wrist.

Cons

  • Some sellers shave thickness by thinning the caseback, which leaves shallow engraving and a weaker gasket seat.
  • Cheap bezels round off the polished edge that the reference keeps crisp against the brushed case band.
  • Lug holes on low-tier cases are often drilled off center, so a strap pulls to one side.

Use case: if the watch will be worn with a suit or a dress shirt, insist on the thinner case and ask for a caliper photo before you commit.

Movement: Asia 7750 Versus a Slimmed Automatic

The genuine watch runs IWC's in-house 69355 chronograph. Replicas do not. The two common options are a standard Asia 7750 dressed with decorated bridges and a signed rotor, or a slimmer 7750 variant built to reduce overall height. Winding feel, pusher travel, and the snap of the reset separate a good example from a rough one.

Pros

  • The 7750 platform is familiar to almost any independent watchmaker, so service and parts are realistic.
  • Decorated bridges and a signed rotor look close to the reference through a display back.
  • A properly regulated 7750 can hold reasonable time across a week of normal wear.

Cons

  • Unmodified 7750 movements add height and can throw off subdial placement.
  • Plated decoration can discolor or flake with hard use.
  • Running the chronograph constantly wears the mechanism faster, and replica movements are not covered by any brand service.

Use case: pick the 7750-based build if you want a watch a local watchmaker can actually open and service. Pick the slimmer build if profile on the wrist matters more than long-term serviceability.

Dial, Hands, and Printing

A Portugieser dial looks simple from a distance: applied numerals, leaf hands, a thin minute track, and two registers. The differences sit in the details. Confirm which register does what on the specific movement inside the watch you are buying, since some 7750-based builds repurpose the counters. Check that printing sits level with the dial axis, that the hands match the reference in length and curvature, and that the subdial rings sit at the correct depth rather than looking stamped on top of the dial.

Pros

  • Top-tier dials use applied indices with polished facets and a genuine sapphire crystal with an inner coating.
  • Correct hand proportions make the watch readable at a glance, the way the reference is.
  • Good printing holds up under a loupe instead of bleeding at the edges.

Cons

  • Cheap dials shift color under indoor light, going flat where the reference stays deep.
  • Short or flat hands are the most common tell on mid-tier builds.
  • Subdial hands are sometimes painted instead of blued or polished, which dims the dial.

Use case: for anyone who handles watches closely or photographs them, spend the extra on dial and hand quality before spending it on anything else.

Case Finishing, Strap, and Buckle

Reference-level finishing alternates brushed band surfaces with polished bezel and lug edges. Replicas vary a lot here. Look for a clean transition line between brushed and polished areas, sharp lug tops, and a caseback engraving that is deep rather than etched lightly. Strap quality matters as much as the case, because a stiff, shiny strap makes even a good case look cheap.

Pros

  • Good builds ship with tapered alligator-grain leather that softens after a week.
  • Buckle engraving on top-tier examples is crisp and correctly sized.
  • Quick-release spring bars on some builds make strap swaps painless.

Cons

  • Budget straps crack at the lug bend within months.
  • Folding clasps on cheaper builds rattle and can sit off center.
  • Polished surfaces scratch faster than the reference because the plating or polish is thinner.

Use case: plan on buying a separate strap if you intend to wear the watch daily. It is the cheapest upgrade with the largest visible effect.

Quick Buying Checklist

  1. Ask for caliper photos of case diameter and thickness, not listing specs.
  2. Confirm which subdial runs seconds and which tracks chronograph minutes.
  3. Request a straight-on dial shot and a true profile shot.
  4. Check the strap taper, stitching, and buckle engraving in close-up photos.
  5. Confirm the return window and whether the seller offers any movement warranty.

Verdict by Use Case

For a daily wearer, choose a 7750-based build with correct 41 mm case geometry so a local watchmaker can service it. For a dress watch where profile matters most, choose the slimmer movement and accept a shorter service life. For a first replica purchase, a mid-tier build with a strong dial and a correct strap is a better entry point than a stripped-down budget piece, because the visible parts are what you will notice every time you look down. Keep in mind that a replica is not a genuine IWC, the brand will not service or authenticate it, and resale value is close to nothing. Budget for an independent watchmaker from the start.