A "fake IW371766" is any watch sold under that IWC reference that did not come from IWC. The number sits in IWC's chronograph line, and chronographs are the hardest watches to copy cheaply, so fakes of this reference fall into two very different groups. Cheap ones get the dial shape roughly right and everything else wrong. Top-tier ones get the case, dial and feel close enough that you need a loupe, a caliper and a look at the movement to tell them apart from the genuine article.
Here is the order I work through when someone hands me one and asks which group it belongs to.
What a fake IW371766 actually is
People use the phrase for three different things. Sometimes it means a counterfeit sold as genuine. Sometimes it means a replica bought knowingly, where the buyer cares about which factory built it and how close the specs are. And sometimes it means a genuine watch that someone suspects, which is a different question with a different answer. Knowing which one you are dealing with changes what you look at first.
Four checks that expose a weak copy
Subdial layout
Chronograph subdial positions are set by the movement underneath, not by the designer. IWC has used both heavily modified Valjoux 7750 bases and in-house chronograph calibres across the 37xx references, and each layout puts the counters in slightly different places with different hand lengths. If a copy is built on a different base, the subdials sit too close together or too far apart, and the hands are the wrong length. Compare against a straight-on photo of the genuine dial and the error shows up fast.
Crystal and dial
Genuine IWC sapphire with anti-reflective coating goes nearly invisible. The dial reads black or blue right up to the edge of the case with no wash of color. A weak copy has no coating, or a single-sided coating that throws a blue or purple sheen, and the dial grays out at an angle. That alone rules out most cheap listings.
Printing and case finishing
Check logo weight and kerning, the thickness of the minute track, and how cleanly the lume sits inside the applied markers. On the case, look at where brushed surfaces meet polished ones. Good finishing has a crisp, straight line between the two. Copies show rounded or wandering transitions, soft lug edges, and a crown that sits proud or sits flush when it should not.
Movement and pusher feel
Start the chronograph. A genuine column wheel or well-tuned cam pusher gives a short, defined click, and the chrono seconds hand snaps back to zero on reset. A cheap 7750 clone feels spongy, the reset hand lags or overshoots, and the rotor wobbles audibly when you tilt the watch. If there is a display back, the movement finishing settles it in seconds. Fakes rarely replicate Geneva stripes, perlage and correct engraving all at once.
The tiers you will see
- Budget: mineral glass, printed or stamped dial furniture, quartz or a rough automatic, wrong case thickness.
- Mid: sapphire crystal, a workable 7750-based movement, decent dial but wrong subdial geometry and weak AR coating.
- Top tier: correct case dimensions, applied markers, accurate printing, correct AR, and a movement that behaves like the real one even if the architecture differs.
What even the best copy gets wrong
Two things. The first is the movement, and it only matters if the reference has a display back. Solid caseback, and the visual gap narrows to almost nothing. The second is long-term serviceability. A watchmaker will work on a modified 7750 all day. A cloned in-house calibre is a different story when it needs parts in five years.
Before you buy
- Ask for photos of the actual watch, including the movement, not catalog images.
- Ask for caliper shots: case diameter, lug-to-lug, thickness. If the seller will not measure, walk.
- Check the return window and whether the seller ships the exact piece photographed.
- Sanity-check the price against the used market for the real reference. A genuine watch at a fraction of market value is not a bargain.
Quick answers
How can I tell a fake IW371766 from a real one?
Start with subdial geometry and crystal coating, then check the printing under magnification and the feel of the pushers. Those four cover most fakes without opening the case.
Are high-tier replicas worth it?
If you want the look and the case feel on the wrist, yes, and that is the whole point of the 1:1 market. If you want the movement or resale value, no copy delivers either.