Short answer
A fake IW329071 gives itself away in four places: case dimensions, dial printing, the date wheel font, and the movement beat rate. Genuine IWC Pilot's Watch references in this family measure 40 mm across the case, sit near 11 mm thick, and run a Sellita-based automatic caliber at 28,800 vibrations per hour. Copies tend to run 41 to 42 mm, print soft-edged text, and use a 21,600 vph movement.
Not every mismatch means counterfeit. IWC has changed dial text, hands, and packaging across production runs, so confirm any single difference against the service documentation for that exact reference before you call a watch fake.
Tools you need
- Digital calipers, or a ruler with millimeter marks
- A 10x loupe
- A phone with slow-motion video
- A watchmaker or IWC service center for the movement check
Step-by-step check
- Measure the case across the middle, crown excluded. Genuine is 40 mm. Allow 0.5 mm for measurement error; anything past 41 mm is a warning.
- Measure thickness from the case back to the top of the crystal. Genuine sits near 11 mm. Copies stack a thick movement and come in at 12 to 13 mm.
- Study the dial under the loupe. The brand line at 12 and the model line at 6 should have sharp edges, even letter spacing, and no ink bleeding into the black.
- Check the date window at 3 o'clock. The aperture should be cleanly cut with a beveled edge, and the numeral should sit centered in the font used on that reference.
- Turn the crown. It should unscrew in about one and a half turns, then wind smoothly with light resistance. A gritty or loose crown points to a cheap tube and stem.
- Inspect the crystal. Genuine sapphire carries anti-reflective coating on the inside only, which gives a faint blue sheen at an angle. A heavy purple or green reflection from the outside means coated mineral glass.
- Charge the lume with a phone light, then watch it fade. Applied markers glow evenly and hold for hours on a genuine watch. Copies glow blotchy and fade within minutes.
- Film the seconds hand in slow motion for ten seconds and count the steps per second. Eight steps is 28,800 vph. Six steps is 21,600 vph, which the factory caliber does not do.
- Read the case back engraving. Reference and serial numbers are laser-engraved with uniform depth. Stamped, shallow, or misaligned digits signal a copy.
- Have a watchmaker open the case. The genuine movement shows the correct caliber number, a signed rotor, and finishing on the bridges. Ask them to compare that number to the reference.
- Confirm with IWC. A service center can verify the serial and reference against factory records, and that check settles the question.
Red flags that need no tools
- A price far below market for that reference, especially from a private seller.
- No box, papers, or service history, combined with a refusal to meet at a watchmaker.
- A seller who will not let the case back be opened.
- Listing photos that avoid the dial at 12 and 6, the date window, and the case back.
What to do if you already bought one
Stop wearing it and do not resell it as genuine. Selling a counterfeit watch is illegal in the United States, and the buyer can pursue a refund. If you paid by card or through a platform with buyer protection, open a dispute with the photos and measurement notes you collected. Keep the listing text and any chat messages, since those are the evidence that decides the case.