Short Answer
A fake IW371647 is any watch stamped with that IWC reference number that was not built by IWC Schaffhausen. The number sits inside the Portugieser Chronograph family, so a replica has to match a fixed set of numbers: case diameter, case thickness, lug width, dial layout and the movement behind the caseback. Almost every replica misses at least one of them. The three checks that separate a decent copy from a poor one are case measurement, chronograph pusher action and dial printing under magnification.
Before You Start
- The factory specification for IW371647, taken from IWC's own catalogue or from an authorized dealer
- Digital calipers that read to 0.01 mm
- A 10x jeweller's loupe
- A kitchen scale accurate to 1 gram
- A phone or camera that shoots macro photos
- Reference photos of a genuine example from the same reference and dial colour
How to Evaluate a Fake IW371647
- Pull the official build sheet for IW371647 and write down case metal, dial colour, strap material and lug width.
- Measure the case with digital calipers across the bezel and record the number.
- Measure case thickness from the caseback to the top of the crystal with the crystal in place.
- Weigh the watch head without the strap and compare it to the expected weight for a steel Portugieser of that size.
- Start, stop and reset the chronograph three times and note whether the pushers travel short and crisp or feel spongy.
- Slide the crown out to each position and check that the date and time setting clicks cleanly with no grinding.
- Inspect the dial at 10x and check that applied numerals sit flat, that printed text has hard edges and that no ink has bled into the subdial rings.
- Compare subdial centres against reference photos and confirm the hands reach the correct track marks.
- Photograph the caseback engraving with light raking across the surface and check engraving depth and letter spacing.
- Look at the movement through the display back and compare rotor engraving, perlage, screw colour and overall layout to published photos of the calibre IWC fits to that reference.
Flaws That Show Up Most Often
Replica Portugieser Chronographs fail in predictable places. A case that measures 0.5 mm to 1.5 mm over spec is the most common fault, and it usually comes with a taller crystal and a distorted bezel profile.
- Case thickness above the factory figure
- Pushers with long travel, a soft return or a stuck reset
- Dial print that looks fuzzy under a loupe
- Polished chamfers that are rounded instead of sharp
- Shallow caseback engraving in the wrong font
- Strap width at the lugs that does not match the reference
Legal Reality in the United States
Selling a watch as an IWC product when it is not one is trademark infringement, and importing counterfeits is illegal in the United States. Shipments can be seized by US Customs and Border Protection, and the buyer loses both the watch and the money. Treat any replica as a replica, price it as a replica and never pass it on as a genuine IW371647.