The short answer: buy the replica IW371634 only if it matches the genuine 41 mm case, 13.1 mm thickness, and two-register dial with subdials at 12 and 6 o'clock. If the case is thicker than 14 mm or the subdials sit at 3 and 9, walk away. Those two flaws ruin the look more than any logo.

What to look for in a fake IW371634

Start with proportions. Genuine IWC Portugieser Chronograph IW3716 references use a 41 mm stainless steel case that is 13.1 mm thick. The bezel is thin, the lugs curve down, and the lug-to-lug distance stays near 50 mm. A replica that adds 2 mm of thickness or widens the lugs will wear like a different watch.

Next, examine the dial. The IW371634 has a two-register layout: chronograph minutes at 12 o'clock and running seconds at 6 o'clock. There is no date window. Leaf-shaped hands and applied numerals or printed indices should look crisp. The dial color must match the reference you want, whether silver-plated, blue, or black.

Movement matters for function and feel. Most replicas use a Seagull ST19 manual-wind chronograph or a modified Valjoux 7750 automatic. The ST19 gives a smooth pusher feel and a column-wheel design that is closer to the genuine 69355 calibre. A 7750-based replica often has a thicker case and a rotor that spins loudly. Ask which movement is inside before you commit.

Parameter bands to compare

  • Case diameter: 40.8 to 41.2 mm. Reject anything 42 mm or larger.
  • Case thickness: 13.0 to 13.5 mm. Over 14 mm looks slab-sided.
  • Lug-to-lug: 49 to 51 mm. This decides comfort on a 6.5 to 7.5 inch wrist.
  • Subdial spacing: 12 and 6 o'clock, centered on the vertical axis. No date window.
  • Crystal: sapphire with double anti-reflective coating. Mineral glass scratches.
  • Water resistance: 3 to 5 ATM in practice. Do not swim with a replica.
  • Weight (head only): 75 to 100 g. Too light means hollow case.

Common pitfalls

  • Wrong subdial positions at 3 and 9. This is the most common tell.
  • A date window at 3 o'clock. The genuine IW371634 does not have one.
  • Printed Swiss Made with wrong font or spacing at 6 o'clock.
  • Mineral glass instead of sapphire, which shows scratches in weeks.
  • Weak anti-reflective coating, causing a mirror-like glare.
  • Pushers that feel gritty or need force to start the chronograph.
  • Caseback engraving with shallow laser etching and wrong reference number.
  • Strap hardware that is stamped rather than brushed or polished.

FAQ

Is a fake IW371634 worth buying?

It can be if you accept it as a design tribute. Focus on the case and dial. A mid-tier replica with correct subdials and a sapphire crystal gives the best visual value.

How can I spot a low-quality replica quickly?

Check thickness and subdial spacing. If the watch is thicker than 14 mm or the subdials sit at 3 and 9, it is wrong.

What movement should I expect?

Seagull ST19 or a 7750 clone. The ST19 is manual wind and closer in spirit. The 7750 is automatic but often thicker.

Can a watchmaker service a replica?

Some will, many will not. Ask before you buy. Parts for ST19 and 7750 clones are available, but labor costs can exceed the watch value.

Will it pass as a genuine IWC?

No. Experts will spot the movement or caseback. Enjoy the look without pretending.