Short answer

IW371775 belongs to the IWC Portugieser Chronograph line. The watch is a steel chronograph with two subdials, a date at 3 o'clock, and pushers at 2 and 4. Replica versions of this reference differ from each other in case size, dial print, and movement. Price tracks those three things. No replica runs an IWC movement.

I could not confirm the exact suffix "775" in IWC's public catalog. The Portugieser Chronograph references I can verify are IW3714xx (40.9 mm, calibre 79350) and IW3716xx (41 mm, calibre 69355). Treat "IW371775" as a dial and strap code inside that family. Compare seller photos against both generations before you pay.

Numbers on the genuine watch

  • Case: stainless steel, 40.9 mm (IW3714) or 41 mm (IW3716)
  • Height: about 12.3 mm (IW3714) and 13.1 mm (IW3716)
  • Crystal: sapphire, antireflective coating on both faces
  • Caseback: sapphire display, four screws on the 3716
  • Water resistance: 3 bar, rated for splashes
  • Movement: calibre 79350 (Valjoux 7750 base) or in-house calibre 69355
  • Power reserve: 44 hours (79350), 46 hours (69355)
  • Dial layout: running seconds at 6, chronograph minutes at 12, date window at 3

Replica tiers and what changes

Tier one uses a quartz movement. Subdials are often decorative or run as 24-hour and day indicators. Case thickness sits above 13 mm on most samples. Expect a printed date wheel and a mineral crystal.

Tier two uses an Asian 7750 clone. That gives a working chronograph with the correct subdial function. The trade is thickness, rotor noise, and a reset that can drift. Movement finishing is basic.

Tier three uses a decorated clone with a copied rotor engraving. Dial print improves, hands get closer to the original shape, and the crystal gains an antireflective coat. Subdial spacing is the common failure point here. On the genuine 3714 the two subdials sit close to the center line. On many replicas the gap is wider.

Photo checklist before buying

  1. Ask for a straight-on dial photo and measure the subdial centers against a known photo of the genuine watch.
  2. Check the date window position. It should sit on the 3 o'clock axis, level with the subdial centers.
  3. Look at the printed minute track. Uneven spacing shows at 6 and 12.
  4. Ask for a caseback photo. The engraving depth and font weight are the second tell after the dial.
  5. Request a video of the chronograph start, stop, and reset. A jumping minute counter is a fault.
  6. Ask for a side profile shot with calipers. Report the number, not an estimate.
  7. Confirm strap type and lug width. The 3714 takes 20 mm, the 3716 takes 20 mm.

Limits to expect

Water resistance on a replica is not tested to 3 bar. Do not swim with one. Service support does not exist, so a movement fault means a local watchmaker or a replacement. Plating on gold-tone versions wears at the lugs and caseback edge. Resale value is near zero.

Check local law before you buy. Sale of counterfeit goods is illegal in the US and the EU, and customs seizures happen.