The short answer to the fake IW371431 question: on an IWC Portugieser Chronograph, the reference-number format, the case-back engraving and the movement are the three things a copy cannot get right at a glance, so check those before you study the dial. The criteria below are the ones buyers use, ordered so that the cheapest checks come first: does the reference exist as stated, does the movement behave like a 7750-based chronograph, is the dial printing crisp at sub-dial level, does the case feel and finish like a Portugieser, and do the box, papers and price hold together.
Step one: verify the reference number itself
IWC Portugieser Chronograph references sit in the IW3714xx family, so a seller quoting "IW371431" needs to show that exact suffix on the case back and on the warranty card, matching digit for digit. Ask for a clear photo of the engraving between the lugs and the number on the card in the same frame. Vague answers about the suffix, or a card that shows a different last two digits, are a stronger warning than any dial detail.
- Pros: costs nothing, takes one photo, and filters out mismatched paperwork fast.
- Cons: a careful counterfeiter can copy a real number onto a fake case back, so this check rules out sloppy fakes only.
Step two: movement and chronograph action
Most IW3714 references run a chronograph movement derived from the Valjoux 7750 family, which has a distinct feel: a firm pusher start, a crisp reset snap and a rotor that spins with a light wobble when you tilt the watch. Ask for a short video with the chronograph started, stopped and reset. A sluggish reset, a pusher that mushes through its travel, or a seconds hand that jumps on start rather than sweeping smoothly are all signs of a cheap quartz or low-grade mechanical copy.
Fake IW371431: What the Best Portugieser Replica Gets Right
- Pros: movement behaviour is hard to fake and easy to record on video.
- Cons: you need a seller willing to film the watch running, and a service-replacement movement can mimic the feel.
Step three: dial printing, hands and sub-dials
Look at a macro shot of the sub-dials, not a wide shot of the whole watch. On a genuine dial the printing sits flat and even, the applied numerals have sharp inner corners, and the sub-dial hands are finished on all sides. Copies tend to show thicker print, sub-dials spaced a fraction too close to the centre, and hands with flat, unfinished edges. At 40.9 mm with a thin bezel, the Portugieser case leaves the dial very exposed, which makes flaws easier to spot than on a thick sports watch.
Step four: case, crystal and finishing
Run a fingernail along the lugs and around the bezel edge. Real Portugieser cases have polished surfaces that meet brushed surfaces on a clean line, and the crystal sits close to flush. Copies commonly show rounded lug edges, a gasket ring visible under the crystal, and a case that feels light for its size. Weight alone proves nothing, but a watch that feels hollow next to a known reference is worth a second look.
Step five: box, papers and price sanity
Compare the asking price against current secondary-market listings for the same reference and condition. A price far below the market band for a "full set" watch is the oldest signal there is, and it usually means either a replica, a stolen watch or a rebuilt watch with mismatched parts. Ask which service history exists and who performed it.
Replica or the real thing: what each option gives you
If the goal is the Portugieser look on a smaller budget, a high-grade 1:1 replica gets the case proportions, dial layout and strap right, and it will pass a glance across a table. It will not pass a loupe, a case-back photo or a movement video, and it will not hold value. The genuine watch costs several times more, needs servicing, and holds resale far better.
- Replica pros: correct 40.9 mm proportions, convincing dial furniture, low entry cost, no service bills.
- Replica cons: fails movement and case-back checks, no resale value, water resistance is a guess, no warranty support.
- Genuine pros: verifiable reference and papers, serviceable movement, real resale market.
- Genuine cons: high purchase price, service intervals and costs, longer saving period.
Use case: if you are buying to wear with the look of a Portugieser and you accept that it is a copy, buy from a seller who shows movement video and accepts returns. If you are buying as an investment or a keeper, save for the real reference and have it checked by a watchmaker before money changes hands.