Short answer
A fake IW371498 is almost always a replica of the IWC Portugieser Chronograph built on a generic Valjoux 7750 base and sold as the genuine article. The tells cluster in four spots: the subdial layout, the date wheel, the caseback engraving, and the feel of the chronograph pushers. If a seller will not show you those four things in sharp photos, assume fake and walk.
What the 371498 is supposed to be
The reference sits inside the Portugieser Chronograph line, so everything known about the 3714 family carries over. A genuine example gives you a two register chronograph: elapsed minutes at 12, running seconds at 6, date at 3. The case is 40.9 mm in steel, about 12.3 mm thick, rated to 3 bar. Leaf shaped hands, applied Arabic numerals, sapphire front and back, and a strap that tapers toward a signed pin buckle. Nothing about that spec sheet is exotic, which is exactly why the reference gets copied so often.
Tells you can catch on the wrist
- Subdial layout. A stock 7750 has three register positions, so a lazy fake either leaves a dead third subdial or blanks it out with a printed plate. On a real 371498 the 12 and 6 registers sit centered on their own axes and the hands sweep without stutter.
- Date wheel. Replicas use generic date discs. The font is too wide, the numbers sit off center in the aperture, and the window edge is unfinished.
- Pushers. Genuine pushers have a short, dry travel and a crisp reset. Most fakes feel spongy and need a longer throw to start the chronograph.
- Numerals and hands. Applied indices on a fake are often glued or slightly rotated. The leaf hands can look flat because the bevel is stamped, not polished.
- Weight and thickness. A 7750 with a decorative plate runs thick. If the watch sits tall under a cuff or feels light for a steel chronograph, that is a signal.
Caseback and movement checks
Flip it over. Genuine engraving on the caseback rim is cut deep with crisp edges and consistent letter spacing; laser etched fakes look shallow and grey. Between the lugs you should find a reference and serial number stamped into the metal, not printed on a sticker. Through the display back, IWC finishes its movements with Geneva stripes on the bridges and a signed rotor, and the perlage is tight and even. Cheap replicas either plate the movement or leave machining marks visible under the rotor. One more detail: the sapphire crystal on a real IWC carries a faint blue anti reflective tint at certain angles. Plenty of fakes skip this entirely.
Where good replicas still fall short
Higher end copies get the case proportions close and can fool someone across a table. They still struggle with three things: the date font, the sound and feel of the winding, and long term reliability of the chronograph module. A cheap copy of a 7750 that was never serviced will lose time, and the pusher return spring is often the first failure. If you own one, budget for a service or accept that it is a costume piece.
Legal reality in the US
Selling or importing counterfeit watches is illegal in the United States, and customs does seize shipments. That matters when you are shopping, because a seller who will not put anything in writing is protecting themselves, not you. A watch described as a replica should be priced and labeled as one. Anything sold as genuine at a genuine price is fraud.
Checklist before you commit
- Ask for a macro shot of the date window and both subdials.
- Ask for the caseback rim and the engraving between the lugs.
- Ask for a photo of the movement through the display back.
- Ask for the reference and serial in writing, then verify the reference matches the dial configuration.
- Compare the asking price against the current market for a genuine example. A deep discount on a steel Portugieser Chronograph is the oldest tell there is.