A fake IW371770 is a counterfeit copy of the IWC Portugieser Chronograph, and the fastest tell is the subdial layout. On a genuine watch the two chronograph subdials sit at 12 and 6 with even spacing to the outer minute track, while the date window at 3 is recessed into the dial behind a crisp metal frame. Most replicas pull the subdials toward the center, print the date window flat, and use a date font that is too heavy for the dial.

What is the IW371770?

The IW371770 sits in the IWC Portugieser Chronograph family, a line defined by a 41 mm case, leaf-shaped hands, a railway minute track, and two vertical subdials. The reference pairs a stainless steel case with sapphire crystal and a self-winding chronograph movement. Modern production uses an IWC in-house column wheel caliber, while earlier 3717 references used a heavily modified Valjoux 7750 base, and that difference matters when you inspect a suspect watch.

How do you spot a fake IW371770?

Work from the outside in: dial, case, movement, then paperwork. Each layer filters out a different grade of counterfeit, from low-cost street copies to the better-built super clones sold online.

Dial and hands

• Subdial spacing: real dials align both subdials to the printed minute track; replicas leave them closer to the center pinion.
• Printing: IWC uses thin, sharp lacquer. Fakes show thick, slightly fuzzy text and uneven Schaffhausen lettering.
• Date wheel: the numeral font should match the dial print. Clone date wheels use generic fonts and often sit off-center in the window.
• Hands: leaf hands are polished on every facet on the real watch and look flat under a loupe on a fake.

Case, crystal and pushers

A genuine case measures 41 mm across and roughly 13 mm thick, with soft polished bevels along the lugs. Replicas usually run thicker or thinner and lose the bevel line entirely. Double-sided anti-reflective coating makes a real dial look almost glass-free, while many clones coat one side only, and genuine chronograph pushers have a short, firm travel that clone pushers rarely match.

Movement

The largest gap is inside the case. Modern genuine IW371770 watches run an in-house chronograph caliber with a column wheel and a long power reserve. Replicas almost always use a Seagull ST19 or a decorated 7750 clone, which you can identify through the sapphire caseback by balance wheel position, rotor engraving depth, and a subdial layout that does not match the reference.

Caseback, strap and paperwork

Caseback engraving on a real watch is deep, centered, and consistent in letter spacing, including the reference number and serial. Clone engraving is shallow and often laser-etched with a softer edge. Genuine alligator straps carry even stitching and a signed deployant clasp, while replica straps use embossed leather, and the included papers and warranty card rarely match the serial on the case.

Why is the IW371770 copied so often?

The Portugieser Chronograph has a clean, simple dial that is easier to reproduce than a skeletonized or gem-set design. Demand for a dress chronograph under luxury pricing keeps replica factories iterating on this reference year after year. The result is a wide market of fakes at many quality levels, which is exactly why the dial and movement checks matter more than the box or the seller story.

What does a real IW371770 cost compared with a fake?

Genuine Portugieser Chronograph watches typically trade in the mid four figures to low five figures in US dollars on the secondary market, depending on dial color, year, and whether the full set is included. Replicas usually sell between a few hundred and roughly a thousand dollars. If a seller offers a steel IWC chronograph with in-house caliber specs at a fraction of market price, the watch is almost certainly a copy.

Frequently asked questions

Can a fake IW371770 pass a visual check?

At arm's length a good replica can look convincing, but side-by-side comparison exposes subdial spacing, dial print weight, and crystal reflections. A loupe and a caseback view settle the question in seconds.

Do fake IW371770 watches use real movements?

No. They use third-party chronograph movements with decorative plates and engraved rotors meant to imitate IWC finishing. Service, parts, and accuracy all differ from the genuine caliber.

Is the reference number enough to verify authenticity?

No. Reference numbers are printed on the caseback of replicas as well. Verification needs the serial, service history, and an inspection by a watchmaker or an authorized service center.