Short answer

IW371789 is an IWC-style reference number: the letters IW plus six digits. It sits close to the Portugieser Chronograph range, which IWC lists under IW3714xx and IW3716xx. IWC's public catalog does not show a confirmed IW371789 entry. That matters for a buyer. A replica sold under an unconfirmed number cannot be compared against a real watch, because no published spec sheet exists for it.

Baseline specs for the IW3716 family

These numbers apply to the current Portugieser Chronograph. Confirm them against IWC's site for any other reference.

  • Case: 41.0 mm steel, 13.0 mm thick
  • Movement: in-house calibre 69355, column wheel chronograph
  • Power reserve: 46 hours
  • Water resistance: 30 m
  • Crystal: sapphire, antireflective coating on both faces
  • Dial: two subdials, running seconds at 6, chronograph minutes at 12, date at 3

What replica listings claim

Most sellers use three labels: 1:1, Swiss movement, and 904L steel. Treat each as a claim, not a spec.

  • Movement: the common base is an Asian Valjoux 7750 clone with a decorated rotor. Genuine Swiss ETA 7750 stock is limited and costs more than most replica prices allow.
  • Steel: 904L is rare in this price band. 316L is the norm.
  • Subdial layout: a 7750 puts subdials at 6, 9 and 12. Makers add a false plate to reach the 6 and 12 layout, which changes hand height and pusher feel.

Checks before you pay

  1. Ask for caliper photos of the case. Target 41.0 mm, not 42 or 40.
  2. Ask for a timegrapher photo. Rate inside plus or minus 10 seconds per day, amplitude above 250 degrees.
  3. Look at the date window. It should sit at 3, aligned with the crown.
  4. Check dial print under 10x magnification. Thick, merged letters signal pad printing, not applied markers.
  5. Read the caseback engraving. Shallow laser marks differ from deep stamped text.
  6. Confirm the seller names the movement model in writing.

Cost and legal risk in the US

Trafficking in counterfeit goods is a federal crime under 18 U.S.C. 2320. US Customs and Border Protection seizes counterfeit shipments and notifies the trademark owner. A seized parcel is not refunded by the carrier. Buyers who pay by card or wire have little recourse when a package is held.

Verification step

Open IWC's reference list and search the exact number before any payment. If the number returns no result, ask the seller for the source of the reference. A seller who cannot name the source is selling a watch with a made-up model code.