The short answer
Fake IW371759 watches exist, but most of them are crude. The dangerous ones are the high tier copies that match the case and dial at arm's length. They still fail under a loupe at the movement, the date wheel, and the caseback engraving. If you are spending real money on a used IWC chronograph, treat the reference number as a starting point, not proof. Confirm the exact spec with IWC, then verify the individual watch.
Why this reference gets copied
IWC chronographs in the 3717 reference block sit in a sweet spot for counterfeiters. The design is clean, the dial is easy to photograph, and the real thing costs enough that a copy at a tenth of the price looks tempting. Demand also comes from people who want the look without the service bill. That mix keeps a steady supply of listings on classifieds sites and social marketplaces, which is where most bad watches surface.
What to check before you compare anything
Reference numbers get misquoted in listings all the time, and some fakes borrow a number from a different dial variant. Pull the official spec first: case diameter and thickness, lug width, crystal shape, movement calibre, and the dial color tied to that reference. Write those numbers down. Everything after that is a comparison against a fixed target.
Outside tells
- Dial printing: look at the minute track and the text under 12. Genuine printing sits sharp under a loupe. Copies show fuzzy edges, uneven spacing, and a logo that runs thick.
- Subdial placement: measure the gap between the two registers and the center. Copies shift them a fraction, and the dial ends up looking crowded near the date window.
- Hands and lume: hands should reach the track. On fakes they run short, with flat finishes and sloppy lume edges.
- Case finishing: brushed and polished surfaces should meet on a crisp line. Run a fingernail along the transition on the lugs and the case sides.
- Crystal: genuine sapphire has a clean anti reflective coat. Cheap copies reflect like a mirror or show a blue tint from the wrong angle.
- Crown and pushers: check the engraving, the thread feel, and whether the pushers return with a firm click.
The movement is where copies break down
Ask for a photo of the caseback and the movement, or a short video with the second hand running. Genuine IWC chronographs in this family use a Swiss chronograph calibre with a smooth sweep and a clean reset to zero. Many fakes run a modified Asian 7750 copy, which shows a stutter on the sweep, a wandering reset, and rotor noise you can hear across a room. A timegrapher reading is the cheapest test you can ask a seller to provide. If they refuse, that is the answer.
Serial, box, and papers
A serial number on the caseback means nothing on its own, since fakers engrave plausible numbers. What matters is whether that serial checks out with an IWC service center or an authorized dealer, and whether the number on the case matches the one on the papers. Boxes and booklets are easy to fake and easy to buy empty, so treat them as a secondary signal. A service invoice with a real watchmaker's name and a matching case number carries more weight.
Price logic
Run the math before you get excited. If a listing sits far below the going rate for that reference in that condition, the seller either does not know what they have, or the watch is not what it claims to be. The second option is far more common. Genuine chronographs from this era also carry upcoming service costs, so a cheap watch with no history can end up costing more than a clean one with paperwork.
A short checklist for a used purchase
- Get the reference number and confirm the spec with IWC.
- Request sharp photos of the dial, caseback, crown side, and the movement.
- Ask for a timegrapher reading or a video of the chronograph start, stop, and reset.
- Verify the serial through a service center or authorized dealer.
- Meet a watchmaker for an inspection, or use an escrow service with a return window.
- Walk away from pressure, wire transfers to strangers, and sellers who will not show the movement.
If you already bought one
Take it to an independent watchmaker who handles IWC. They can confirm the calibre, check the case number, and tell you whether the parts are genuine. If the watch is a fake and you paid through a platform with buyer protection, file the dispute fast and keep every message. If you paid by wire, your options shrink, which is why the payment method belongs in your checklist before the watch does.