Short answer
A fake IW371717 is a copy of the IWC Pilot's Watch Chronograph from the 3717 family. The genuine watch has a 43 mm steel case, an IWC calibre 79320 movement, day and date at 3 o'clock and a soft-iron inner case for antimagnetic protection. Most copies miss the movement finish, the inner cage, the crown feel and the antireflective coating on the crystal.
Used genuine examples sell for about USD 3,500 to 6,000 with box and papers. Replica examples sell for about USD 250 to 700. Price alone proves nothing, because sellers price bad copies high.
What the reference number covers
IWC reference numbers carry an IW prefix followed by digits. The 3717 base covers Pilot's Watch Chronograph versions built from 2006 to about 2012. Variants seen in listings include 371701, 371704, 371705 and 371706. A published data sheet for the exact string 371717 is hard to verify, so treat that number in a listing as a description, not as proof. Confirm the reference and the serial on the caseback and on the papers.
Genuine specs to compare
- Case: 43 mm stainless steel, 14.8 mm thick
- Movement: IWC calibre 79320, Valjoux 7750 base, 25 jewels, 28,800 vph, 44 hour power reserve
- Dial: small seconds at 9, chronograph minutes at 12, chronograph hours at 6, day and date at 3
- Crystal: convex sapphire with antireflective coating on both faces
- Water resistance: 60 m
- Caseback: solid steel, engraved, with a soft-iron inner case behind it
Where copies fail
- Movement: clones show tool marks on the balance cock and shallow rotor engraving. Genuine 79320 rotors carry deep, crisp lettering.
- Date and day discs: wrong font weight and a yellow or grey tone instead of white print on black.
- Crystal: single-side coating leaves a white sheen. Genuine double-side coating shows a blue or violet tint at an angle.
- Lume: uneven fill on the hands and numerals, with drag marks at the edges.
- Caseback: soft engraving, wrong letter spacing, and a serial that repeats across listings.
- Weight: zinc alloy and brass shells feel light in the hand compared with a steel case.
Checks that need no tools
- Press the chronograph start pusher. A 7750 family movement gives a firm click and the center seconds hand jumps with no lag.
- Pull the crown to position 2 and turn it. Day and date should advance in opposite directions on the genuine watch.
- Hold the crystal under a desk lamp and rotate the watch. Look for the blue tint on both faces.
- Take a macro photo of the dial and compare subdial ring thickness and print weight with a known photo.
- Ask for a movement photo with the caseback removed, or a timing print showing rate, amplitude and beat error.
What 1:1 and first copy mean
Both terms are marketing. They carry no technical meaning. Ask the seller for the movement name, the case metal, the crystal coating type and photos of the crown, pushers, dial print and caseback. A seller who cannot name the movement is guessing.
Cost and risk
Counterfeit watches that carry a protected brand mark are illegal to import into the United States. Customs can seize the shipment, and the buyer loses the money. Transactions on social apps and classifieds give no refund path. Payment by bank transfer or crypto leaves no chargeback option.