Short answer: a replica IW371741 is a copy of the IWC Portugieser Chronograph, and the ones worth buying get the case proportions, the two-register dial, and an automatic chronograph movement close enough that the difference only shows under a loupe. Everything else, the box, the papers, the story about a dealer in Singapore, is noise. Below is how I judge one before spending money.
Genuine specs to hold the copy against
You cannot spot a good copy without knowing the original. The Portugieser Chronograph is a simple watch on paper, which is exactly why sloppy replicas stand out.
Case and proportions
Roughly 40.9 to 41 mm across, about 12 mm thick, 20 mm between the lugs. Thin bezel, narrow lugs, flat caseband, and a caseback that sits close to the wrist. IWC rates these references for light contact with water only, in the 3 to 5 bar range depending on the generation, so it was never a swim watch to begin with.
Dial and hands
Silver-white or blue dial, printed minute track, applied Arabic numerals, leaf-shaped hands. The small seconds sits at 6 o'clock and the 30-minute chronograph counter sits at 12, both on the vertical center line, with the date at 3. On a weak copy those subdials drift off axis, sit too far inboard, or carry hands that stop short of the minute track.
Movement
Older genuine references used a modified Valjoux 7750, sold as IWC calibre 79350. Current production uses the in-house 69355. Both beat at 4 Hz. Replicas almost always run a Chinese 7750 clone, which is a genuine automatic chronograph with a working sweep, reset, and date. The cheapest versions are quartz, and you can feel it the moment you press a pusher.
Strap and buckle
Alligator leather on the original, 20 mm at the lugs, with a signed tang or deployant buckle. Rep straps are usually the first part to fail, so budget for a replacement.
What separates a good copy from a bad one
- Subdial position and diameter. This is the fastest tell from across a table.
- Case thickness. A domed caseback adds 1 to 2 mm and ruins the silhouette.
- Date window placement and font weight. Copy text almost always runs too thick.
- Anti-reflective coating. Heavy purple tint looks wrong, and no coating at all looks flat.
- Hand length against the printed track. Short hands are common.
- Reliability of the seconds-at-6 layout. Running small seconds at 6 on a 7750 base adds a gear train that wears over time. Ask the seller what happens if it stops.
Before you pay, ask these
- Which movement, and is the chronograph functional or decorative.
- Measured diameter and thickness in millimeters, with calipers visible in the photo.
- Photos of the caseback, crown, and buckle, not just the dial.
- Whether the watch was timed, and what rate it holds.
- Return policy, and who pays shipping if it arrives damaged.
What they cost
Decent automatic examples usually land between $250 and $500. Under $150 you are looking at quartz or a case that feels wrong in the hand. Above $600 you are paying for a name rather than a better watch.
Living with one
Keep it out of water regardless of what the listing claims. Wind it gently, do not leave the chronograph running around the clock, and expect to change the strap within a year. Treat it as a watch rather than an heirloom and it will do exactly what you bought it for.