Short answer
A fake IW371787 is a replica of an IWC Pilot's Watch Chronograph from the 3717 reference family, not a model that IWC sells. Authentication comes down to four checks you can complete in a few minutes: the dial print and subdial positions, the case back engraving, the movement visible through the display back, and the serial number matched against the paperwork. Most copies fail at least one of those checks.
Why this reference gets copied
The 3717 Pilot's Chronograph was produced through the 2000s and early 2010s, which means the market is full of used examples, and used watches are easy to counterfeit. The design is also simple to imitate at a glance: a matte black dial, large Arabic numerals filled with luminous paint, a day and date window at 3 o'clock, and three subdials driven by a chronograph movement. A replica maker only needs the outer look to sell a watch to a buyer who never opens the case.
That gap between appearance and internals is exactly where the fake IW371787 shows itself.
Dial and hands: the fastest tells
Print quality is the hardest thing to copy well. On a genuine dial, the numerals sit flat and even, the minute track is sharp under magnification, and the luminous fill sits level inside each numeral with no overflow. Replicas usually show at least one of these problems:
- Luminous paint that spills over the printed edge of the numerals or the hands
- Subdials positioned slightly off from the true centers, most often the 6 o'clock counter sitting low or high
- Day and date discs with the wrong typeface, uneven spacing, or a misaligned date that does not snap to center
- Hands with a flat, printed finish instead of polished edges and a clean sweep
- Dial text that is too thick, too thin, or spaced differently from the original layout
Case back, engraving and serial numbers
Genuine case backs carry crisp, deep engraving with clean letter edges. Replica engraving tends to look shallow, rounded, or laser-etched with a slightly frosted finish. Check the reference number, the case material marking, and the serial. Then compare the serial to any card, booklet, or service record that comes with the watch. A serial that does not match the paperwork, or a card printed with a generic model name instead of the exact reference, is a strong warning sign.
Movement checks
The 3717 family uses an IWC calibre built on the Valjoux 7750 architecture. If the watch has a display back, look at the finish: rotor engraving, perlage on the plates, blued or polished screws, and a balance that oscillates smoothly when you rotate the watch. Replicas commonly run an Asian clone of the same 7750 layout, and the shortcuts show as rough rotor finishing, uneven engraving depth, and a chronograph that stutters or fails to reset to zero. Quartz movements found inside a supposedly mechanical chronograph end the discussion immediately.
Box, papers, and provenance
Fake boxes are easy to buy, so packaging proves very little on its own. Treat it as supporting evidence only. What matters more is a documented service history, an original receipt from an authorized dealer, or a recent service invoice from a watchmaker who has handled the movement. Ask who performed the last service and when.
Questions to ask before you buy
- Can you send sharp photos of the dial under magnification, the case back, and the movement?
- What is the full serial number, and does it appear on the paperwork?
- Has the watch ever been serviced, and by whom?
- Will you accept a return if an independent watchmaker finds the movement is not correct?
- Can I meet at a watchmaker for inspection before money changes hands?
A seller who avoids any of these questions is telling you something useful.
Practical and legal notes
Selling a counterfeit watch as genuine is illegal in most markets, including the United States, and buying one knowingly carries risk of seizure and loss of funds. If you want the look of the reference without the price of an original, buy a legitimate homage or a different brand outright rather than a watch presented as something it is not. If you already own a suspected fake, a watchmaker can confirm the movement in minutes, and that confirmation is worth having before you list, trade, or repair it.