A fake IW371766 gives itself away in four places: the chronograph pushers, the dial print, the caseback engraving, and the movement you can see through the sapphire back. Real IWC Portugieser Chronographs run an in-house column-wheel caliber (69355 in the current 41 mm line), so the pushers start with a light click and the reset snaps to zero. Most copies use a cam-actuated ETA 7750 derivative or a Chinese clone with a soft start, a stuttering chrono hand, and a shorter power reserve.

What is the IW371766?

The IW371766 sits in the Portugieser Chronograph line, IWC's 41 mm steel chronograph. The family uses the in-house caliber 69355, a column-wheel chronograph with about 46 hours of power reserve and a 30 m water resistance rating. Typical layout: two subdials (chronograph minutes at 12, small seconds at 6), a date window at 3, leaf hands, applied indices, sapphire glass front and back, and an alligator strap on a signed pin buckle.

Reference numbers in the IW3716xx block cover several dial, hand, and strap combinations. Match the exact dial color, hand finish, and strap on IW371766 against IWC's own listing before you judge any single watch. A seller's description is not proof of anything.

Why do people copy the IW371766?

The Portugieser Chronograph has a clean dress-sport dial that reads well in photos, a 41 mm case that fits most wrists, and steady resale interest. Those traits make it a target. Copies range from $60 quartz models on marketplaces to $600 or more for high-grade mechanical versions sold with box and papers.

Price does not settle authenticity. A $700 copy can fool a phone camera, and a real watch can look rough after a hard decade of wear. The checks below work at both ends of that scale.

How do you spot a fake IW371766?

1. Movement and pushers

  • Pusher feel: a real column wheel starts with a short, light click. A 7750 cam system feels longer and heavier.
  • Reset: the genuine chrono hand snaps back to 12 in one motion. Copies hesitate or overshoot the mark.
  • Seconds hand: a 4 Hz beat (28,800 vph) sweeps smooth. Low-beat clones stutter.
  • Power reserve: about 46 hours on a real 69355. Many clones stop near 38.
  • Rotor noise: tilt the watch near your ear and listen for a gritty whir.

Because this reference has a display back, you can inspect the movement without opening the case. A solid caseback on an IW371766 is a warning sign.

2. Dial and printing

  • Check "IWC Schaffhausen" under a 10x loupe: crisp edges, even spacing, flat lacquer.
  • Copies show thick lettering, uneven gaps between words, and a wavy dial finish.
  • Subdial rings and hands should line up with the printed tracks. Misalignment is common in copies.
  • Applied indices sit above the dial with polished facets. Copies use glued or flat stamped markers.
  • Date font should match the rest of the dial print and sit centered in the window.

3. Case, crystal, and finish

  • Measure with calipers. A 41 mm case reads 41.0 mm. Copies drift to 40.2 or 42.5.
  • Lugs mix brushed tops with polished bevels. The transition line should be sharp, not rounded.
  • Sapphire with anti-reflective coating shows a faint blue tint at an angle. Mineral glass shows more, or nothing.
  • Crown engraving is deep and centered. Copies stamp it shallow.
  • Do not water-test a suspect watch, even if the seller claims a 30 m rating.

4. Caseback and numbers

  • Reference and serial numbers sit between the lugs and are cut into the metal, not printed on the surface.
  • The caseback ring engraving is even, with no burrs, and the ring sits flush with the case.
  • Serial numbers should match across the caseback, the warranty card, and any My IWC registration.

5. Strap, buckle, and paperwork

  • IWC alligator straps have fine, regular scales and a soft temper. Cheap straps feel stiff and plastic.
  • Buckles carry the IWC mark, cut sharp and centered.
  • Box, booklets, and card should match the reference. Missing papers show up on real and fake watches alike, so treat papers as one signal among many.

Red flags in a listing or a deal

  1. A price far below the market for the reference, with no explanation.
  2. No movement photos, only stock images, or a phone number instead of a listing.
  3. A seller who refuses a video call, a timestamp photo, or a return window.
  4. A serial number that is missing, scratched out, or different in each photo.
  5. Pressure to pay by wire, gift card, or crypto.
  6. "Unworn, no box" paired with a price that makes no sense.

Quick checklist before you buy

  1. Confirm the reference against IWC's listing for that dial and strap combo.
  2. Ask for 10x macro shots of the dial text, the caseback engraving, and the movement.
  3. Watch a short video of the chronograph start, stop, and reset if you cannot handle the watch.
  4. Get the serial and check it with IWC or an authorized dealer.
  5. Pay with a method that offers buyer protection.
  6. Have a watchmaker confirm the caliber before the return window closes.

FAQ

How much does a fake IW371766 cost?

Copies sell from about $60 for quartz models to $600 or more for higher-grade mechanical versions. A high price does not prove a watch is real, and a low price does not prove it is fake. Judge the watch, not the listing copy.

Can a watchmaker spot a fake IW371766 in one look?

A trained watchmaker needs a few minutes with the movement, not one glance. The column wheel, the finishing on the bridges, and the rotor bearing are hard to fake at a low price. Dial and case checks help, but the movement settles the question.

Is a fake IW371766 worth buying?

A copy does not hold value, cannot be serviced by IWC, and carries no factory warranty. Parts for clone movements are hit and miss. Selling one as genuine is fraud, and it carries legal risk in most countries.

Why do some fakes pass photo checks?

Photos hide texture. Dial lacquer depth, lug bevels, and engraving relief are hard to capture on a phone. Ask for angled natural-light shots and a video of the chronograph running.

If you own one, or you are about to buy

Take the watch to a watchmaker who services IWC or a comparable Swiss brand. A movement inspection costs little next to the price of a wrong purchase. If you sell, expect the same questions you would ask and answer them with photos.