Short answer

IW371776 belongs to the IWC Portugieser Chronograph line. Replica versions sell for $290 to $850. The largest spec gap is thickness. Most replicas measure 13.5 mm to 14.5 mm. The genuine watch measures about 12.3 mm. Ask the seller for a caliper photo before you pay.

The reference number needs a check of its own. IWC lists the current Portugieser Chronograph under the 3716xx family and older steel models under 3717xx. A listing titled 371776 can be a seller code. Ask for a caseback photo and compare the engraving to IWC catalog images.

Genuine specs to compare

  • Case: steel, 41 mm on the 3716 family, 40.9 mm on the older 3717
  • Thickness: 12.3 mm to 13 mm
  • Lug width: 20 mm
  • Water resistance: 30 m
  • Crystal: sapphire, front and display back
  • Movement: calibre 69355 (in-house, 46 h) or 79350 (modified Valjoux 7750, 44 h)
  • Dial: two subdials on the vertical axis, applied numerals at 12 and 6

Movement tiers in the replica market

Tier 1, $290 to $420: Asian 7750 clone. Rotor engraving is shallow. Chrono pushers feel soft.

Tier 2, $450 to $650: the same base calibre with better finishing, blued screws, and a closer rotor print.

Tier 3, $700 to $850: clone with corrected bridges, perlage on the plates, and a serial number that matches the caseback.

None of these are IWC movements. Service parts come from the replica supply chain, not from Schaffhausen.

Checks before you pay

  1. Thickness photo with a caliper resting on the caseback.
  2. Subdial spacing: 12 and 6, centered on the vertical axis.
  3. Date font and window size at 3 o'clock. Compare the numeral shape.
  4. Caseback engraving depth and font weight.
  5. Chronograph reset to zero, run three times.
  6. Weight: 85 g to 100 g for the head.

What replicas get wrong

Case profile: the replica mid-case is thicker, so the lugs sit higher on the wrist. Bevels on the lugs are wider and more polished. The date wheel font is bolder. Rotor engraving uses a laser, not a stamp, so the text shows a brown tint under light.

Water resistance is not tested at the factory. Treat 30 m as a claim, not a rating.

Legal note

US customs can seize counterfeit goods. Sale of a replica marked with an IWC trademark is trademark infringement under US law. Buyers in the EU face similar rules.