The best fake IW371758 is a high-tier build with a working chronograph, subdials at the correct spacing, and a case that stays close to the genuine 41 mm across and roughly 13 mm thick. That is the pick if the watch has to read correctly from a normal talking distance. The criteria behind that call are movement type, dial print and subdial position, case profile, crystal, strap hardware, and how plainly the seller describes what is actually shipping. Every option below is measured against those points rather than against marketing language.

What the IW371758 reference actually is

IW371758 sits inside the IWC Portugieser Chronograph family: a round polished case, a two-register chronograph layout with running seconds at 6 o'clock, a printed minute track around the outer dial, and thin applied numerals. Before comparing copies, confirm the exact configuration on IWC's own reference pages, because dial finish, case metal and strap change the specific details a replica has to reproduce. Reference numbers in this family are easy to confuse, and a seller who cannot state the dial color and case material of the watch they are offering is not a seller worth comparing.

Criteria that decide whether a copy is worth owning

  • Movement: do the pushers start, stop and reset the chronograph cleanly, or are the subdials decorative and frozen?
  • Subdial spacing: on the genuine layout the two registers sit close to the center. Copies built on a stock modular movement push them outward and the dial looks stretched.
  • Case thickness: a chronograph module stacked on a base movement adds height. Measure it; anything approaching 15 mm wears noticeably different.
  • Dial print: check the index thickness, the minute track density and the position of the date aperture if the reference has one.
  • Crystal and caseback: look for a domed sapphire with a real anti-reflective coating, and for engraving that is crisp rather than laser-fuzzy.
  • Seller honesty: the listing should name the movement and the factory tier instead of hiding behind generic wording.

Option 1: High-tier build with a functional chronograph

This is the top pick. These builds use a chronograph movement that actually functions, a case machined to roughly the right proportions, and a dial with the correct two-register layout. The cost sits at the top of the replica range, which is still a fraction of the genuine watch.

  • Pros: correct proportions and subdial spacing; working chronograph; better finishing on the case flanks and lugs; straps that accept genuine-style spring bars.
  • Cons: highest price in the category; service and parts support are effectively nonexistent; water resistance claims are usually unverifiable.

Use case: buy this tier if the watch will be worn regularly and seen up close by people who know watches. It is the only tier where the dial layout survives a side-by-side glance.

Option 2: Mid-tier build with a decorative chronograph

Mid-tier copies often keep the outer look but drop the working chronograph. The pushers may be fixed or may move a hand that resets on its own. Case finishing is thinner, and the crystal is frequently mineral glass or a low-grade sapphire.

  • Pros: meaningfully cheaper; visually acceptable at arm's length; lighter on the wrist if you dislike thick cases.
  • Cons: non-functioning pushers are an instant tell if anyone handles it; subdials are often spaced wrong; plating on gold-tone versions wears through.

Use case: reasonable only if you want the silhouette and will never let anyone press the buttons. Otherwise the savings do not cover the compromise.

Option 3: Quartz and hybrid builds

Quartz versions trade the mechanical feel for accuracy and a low price. The seconds hand ticks rather than sweeps, which is the first thing a watch person notices on a chronograph.

  • Pros: cheapest entry point; accurate timekeeping; almost no maintenance.
  • Cons: ticking seconds hand on a supposedly mechanical chronograph; thin, hollow-feeling case; poor dial printing.

Use case: a novelty purchase at best. It does not answer the question the keyword is asking.

Option 4: Skip the replica and buy a real alternative

A used genuine Portugieser, or a well-regarded mechanical chronograph from a mid-range brand, removes every risk on this list: no customs seizure, no movement failure with no parts, no awkward moment when someone asks to see the back.

  • Pros: real warranty and service network; retained resale value; no legal exposure.
  • Cons: higher entry cost; the specific dial you want may be hard to find used.

Use case: the right call if you plan to wear the watch for years or resell it later.

Legal and practical reality

In the United States, trafficking in counterfeit goods carries criminal penalties under 18 U.S.C. 2320, and shipments are routinely seized by Customs and Border Protection. That means money paid to an overseas seller is usually gone with no recourse. Treat any purchase as final, and never rely on a replica being serviceable, water resistant, or accurately described.

Bottom line

If you buy a fake IW371758, buy the tier with a working chronograph and correct subdial spacing, verify the reference details on IWC's own site first, and accept that the watch is a copy with no support behind it. If those terms do not sit well, the honest alternative costs more but carries none of the risk.