Short answer

A replica IW371787 is a copy of an IWC Pilot's Watch Chrono-Automatic from the 3717 reference family. The genuine watch is a 42 mm steel chronograph with a tri-compax dial, a day-date window at 3 o'clock, and an IWC cal. 79320 movement built on the Valjoux 7750. Replica prices run from about $70 to $600. The movement, the date wheel font, and the subdial hand length are the three places copies show their cost.

What the reference number tells you

IWC uses the first digits for the model family and the last digits for the variant. Reference 371787 sits inside the 3717 run, the Pilot's Watch Chrono-Automatic sold from 2006 into the 2010s. The final digits mark a dial, case finish, and strap combination. Two watches in one family can differ by the suffix alone. IWC's current online catalog no longer carries the 3717 line, so confirm the variant of 371787 against auction photos or owner threads before you use it as a comparison target.

Genuine specs to compare

  • Case: steel, 42 mm across, about 14.8 mm thick.
  • Movement: IWC cal. 79320, automatic, 28,800 vph, about 44 hours of power reserve.
  • Dial: running seconds at 9, chronograph minutes at 12, chronograph hours at 6.
  • Date: day and date in one window at 3 o'clock.
  • Crystal: sapphire with antireflective coating.
  • Water resistance: 6 bar.
  • Inner case: soft iron, for magnetic shielding.

Movements used in replicas

Three groups. Under $150, most copies run quartz or a low-grade automatic with a fake chronograph, where the pushers move the subdial hands in fixed steps. From $150 to $350, sellers use a Chinese 7750 clone or a Seagull movement. Above $350, listings claim a Swiss ETA 7750. Ask for a photo of the movement with the case back off, and ask for the rotor and balance wheel in the frame. A 7750 has subdials at 12, 6, and 9. If the subdials sit anywhere else, the watch is not a 7750 and not a close copy.

Checks that find a bad copy fast

  1. Set the date near midnight and watch the flip. The genuine day and date change as one unit on a 7750. Cheap copies drag or half-flip.
  2. Look at the date wheel font. Copies use a wide, round font with uneven spacing.
  3. Start the chronograph, let it run 60 seconds, and reset. The hands should snap to zero together.
  4. Check the subdial hands. Short, blunt subdial hands are a common flaw.
  5. Look at the crown. The IWC fish logo is stamped, not printed, on the genuine crown.
  6. Check the case back engraving depth. Laser etching on a copy is shallow and gray.
  7. Weigh the watch. A steel 3717 on a strap sits near 100 g. A copy with a hollow case often lands under 80 g.

Price bands

  • $70 to $150: quartz or low-grade automatic, wrong subdial layout, printed crown logo.
  • $150 to $350: 7750 clone, correct layout, weak lume, soft date wheel.
  • $350 to $600: closer case and dial work, better lume, uneven AR coating.
  • Above $700: the same watch as the $400 band in most cases. Treat "Swiss made" claims as unverified.

What no replica copies

Two items. The soft-iron inner case is a real part on the genuine watch, and copies leave it out, so magnetic resistance differs. The IWC movement finish, including Geneva stripes and the engraved rotor, is also absent on a 7750 clone. If either item matters to you, the copy will not match.