The quick version: on an IW371497 you check five things, and you check them in this order. Subdial layout and hands. Crown and pusher feel. The movement behind the display back. Dial printing under a loupe. Caseback engraving against the paperwork. A genuine IWC Portugieser Chronograph passes all five. A fake usually passes two or three and fails the rest, and it is almost always the dial work or the movement family that gives it away.
What the reference should be
The IW371497 sits in the Portugieser Chronograph family, the 3714 line that IWC has built on a steel case of roughly 41 mm for years. The platform details stay consistent across the line: calibre 79350, a reworked Valjoux 7750, two subdials with the 30 minute counter at 12 and running seconds at 6, no date window in the classic layout, feuille hands, applied Arabic numerals, a fine rail track for the minutes, sapphire front and back, and 30 m of water resistance. If the watch in front of you breaks any of that, you can stop looking.
Check one: dial and hands
Put a loupe on it. The printing should be flat and sharp, and the brand mark plus the line under 12 should sit on the same vertical axis as the subdial hands. The minute track should be a hairline, not a thick grey band. The two subdials should match in diameter and sit dead centre, because fakes often build one larger than the other or push one off axis.
The feuille hands should be slender, taper to a point, and carry a slight curve you can catch in raking light. Replica hands are often flat laser cut leaves that read like paddles from the side. The applied numerals should be faceted with polished bevels sitting proud of the dial. On a fake they are frequently glued low, slightly rotated, or finished in a dull satin where there should be a mirror.
Check two: crown, pushers and case
The pushers are the part you feel rather than see. A 7750 based chronograph has a light, crisp start and stop with short travel. Mushy pushers, or a reset that grinds before it snaps back, are not IWC behaviour. Then look at the case flanks: the brushing should be even and unbroken and the polished bevels crisp. Replicas soften the transition between brushed and polished surfaces, and the crown often sits with a visible gap against the case tube.
Check three: the movement
Through the sapphire back, a 79350 shows engraved rotor lettering, striped bridges, blued screws and a balance running at 28,800 vph. That last number is testable without a timegrapher. At eight beats per second the small seconds hand moves in a fine, nearly continuous glide. Some fake chronographs run a Seagull ST19 at 21,600 vph, which is six beats per second, and the stutter is visible on a wrist. Rotor text is the other tell: it should be engraved and filled, not printed onto a decorated plate in the wrong font.
Check four: caseback, serial and papers
The caseback should carry the reference and a serial, cut cleanly with sharp edges rather than lasered into a blurry smear. Cross check that serial against IWC's own reference lookup and a reference database. A number that appears across a dozen forum threads means somebody reused a photograph. On the paperwork side, the warranty card should match the case serial, the booklet should be the correct edition for the year, and the box interior should not smell of fresh glue.
Check five: the price math
A genuine 3714 family Portugieser Chronograph trades in the mid four figures on the secondary market, depending on dial, year and condition. If someone offers a sealed, unworn IW371497 at a third of that and calls it a deal, the conversation is over.
Replica versus fake
A replica sold as a replica is one product. The same watch sold as genuine is fraud, and that is usually why this reference gets searched at all. If you are shopping the replica market instead, judge a 3714 build on the same five points: dial print quality, hand shape, subdial alignment, movement family, and case finishing quality. The gap between a good build and a bad one shows up in the printing and the hands long before it shows up in the case.
Quick field checklist
- Subdials equal in size and on the vertical axis
- Feuille hands tapered to a point, not paddle shaped
- Pushers crisp with short travel
- Small seconds gliding at eight beats per second
- Applied numerals faceted, not glued flat
- Caseback engraving sharp, serial not recycled
- Asking price consistent with the live market