Short answer
A fake IW371471 gives itself away in four places: subdial layout, case thickness, dial printing, and the movement behind the caseback. The genuine IWC Portugieser Chronograph runs a 12 and 6 subdial layout (30-minute counter at 12, running seconds at 6), a stainless steel case just under 41 mm wide and roughly 12.5 mm thick, applied faceted indexes with polished edges, and an IWC-modified chronograph calibre. Most replicas copy a 9 and 3 layout from a generic 7750 chronograph, sit 1 to 2 mm thicker, and print flat numerals on a dial that shows no depth under light.
Prerequisites
- 10x jeweler's loupe
- Digital calipers that read to 0.01 mm
- Small digital scale
- IWC's published spec sheet for the exact reference (diameter, thickness, calibre number, dial code)
- A photo of a verified example of the same reference for side-by-side comparison
Step-by-step inspection
- Open IWC's site or catalog and write down the case diameter, case thickness, calibre number, and dial code listed for the exact reference you are examining.
- Measure the case diameter with calipers across the bezel at 9 and 3, crown excluded, and compare the number to the published figure.
- Measure case thickness from the caseback to the top of the crystal and compare. A reading of 14 mm or more on a steel Portugieser Chronograph points to a replica.
- Look at the subdials. Genuine examples place the 30-minute counter at 12 and running seconds at 6. A 9 and 3 layout is wrong.
- Check hand reach. The minute hand should touch the minute track at the outer edge, and the chronograph hand should land on the index at 12 when reset.
- Put the loupe on the dial text. Letter edges on a genuine dial are sharp and even. Fuzzy edges, uneven spacing, or a thin font signal a counterfeit.
- Study the applied indexes from the side. Originals are faceted with a polished bevel and a brushed top face.
- If the reference has a date aperture, check its position against the 3 o'clock index and inspect the cut edges. Replicas often show a ragged aperture or a wrong date font.
- Turn the watch over and read the caseback engraving. Reference number, serial, and brand text should be cut into the metal with consistent depth, not stamped lightly or laser-etched with a frosted look.
- If the watch has a display back, inspect the rotor and bridges. Genuine IWC finishing shows Geneva stripes, blued screws, and clean engraving of the calibre number.
- Weigh the watch. A steel Portugieser Chronograph on a leather strap lands near 80 g. Replicas usually run lighter because of plated cases and thinner movements.
- Take the watch to an authorized IWC service center or a qualified watchmaker for a movement inspection before you pay.
Price and paperwork tells
A steel Portugieser Chronograph in working condition sells on the secondary market in the mid four figures in US dollars. An offer at a few hundred dollars is a replica, regardless of the story attached to it. Box, papers, and a matching serial help, but printed certificates are easy to fake, so treat paperwork as supporting evidence and never as proof on its own.
Fake IW371471 Watch Comparison
Signals that end the conversation
- Seller refuses an in-person inspection or a service center check
- Serial number does not return a match when you call the brand
- Subdial layout or case thickness falls outside the published specs
- Crystal shows heavy glare with no anti-reflective coating on the inner surface
- Engraving on the caseback looks painted or shallow