Short answer
A fake IW329073 fails on four checks: case diameter and thickness, dial print, caseback engraving, and movement. The real reference sits in IWC's 3290 Pilot's Watch family with a 40 mm steel case, roughly 11 mm thickness, sapphire crystal, screw-down crown, and a soft-iron inner case. Counterfeits copy the shape, not the machining. Run the four checks below before you send money. IWC publishes dimensions and caliber data per reference, so confirm the spec sheet there first.
What reference IW329073 is
IW329073 belongs to the IWC 3290 case family. That platform uses a 40 mm stainless steel case, about 11 mm thick, a soft-iron inner case for magnetic protection, sapphire crystal with antireflective coating on both faces, a screw-down crown, and 6 bar (60 m) water resistance. The automatic movement is IWC Caliber 35111 with a power reserve near 42 hours and a beat rate of 28,800 vph.
IWC reference numbers carry a case code (3290) and a variant code (73). The variant code points to dial, strap, and finishing. A listing that prints "IW329073" next to a 44 mm case is showing a different watch.
Check 1: case and crystal
- Measure the case with calipers. The real width is 40 mm, crown excluded.
- Measure thickness. The real number is near 11 mm. Fakes run thicker and heavier.
- The crystal is sapphire with coating on both faces. Mineral glass scratches and shows no blue tint at an angle.
- The crown threads into the case. Fakes often use a push-in crown that will not seat.
Check 2: dial
- The numerals and the triangle at 12 are printed, not applied, and sit flat on the dial.
- At 5x magnification the print is sharp. Fakes show ink bleed and uneven spacing between markers.
- The date window edges are cut clean and the date wheel centers in the opening. Compare date wheel color against IWC photos for this reference.
- Lume is applied by machine. Fakes show lume past the printed edge or a bumpy surface under light.
Check 3: caseback
Engraving depth, font, and spacing are the fastest tells. A real caseback carries the reference number, the serial number, the IWC name, Schaffhausen, and the water resistance rating. Real engraving is cut into the metal with crisp edges. Laser etching on fakes looks gray and shallow under a loupe.
The reference number and serial number on the caseback must match the warranty card and the movement.
Check 4: movement
A seller who will not open the caseback has answered your question. With the back off, look for IWC engraving on the rotor and the caliber number. Caliber 35111 runs at 28,800 vph, so the seconds hand moves in eight steps per second. A quartz fake ticks once per second. A 21,600 vph fake moves in six steps. A timegrapher reading settles it. Ask for a photo with the reading and the movement in the same frame.
Papers, box, and price
Real kits include a warranty card printed with the reference and serial number, a manual, and a box with correct hardware and typeface. Fake boxes look close. Fake cards do not match the caseback numbers.
US law bans counterfeits. Under 18 U.S.C. § 2320, trafficking in counterfeit goods carries prison time, and Customs and Border Protection seizes shipments at ports of entry. Listings that show a steel IWC at a small fraction of the used market price are selling a fake or a stolen watch.
Where to verify
- Match caseback numbers to IWC's own reference listing.
- Take the watch to an IWC boutique or service center. Opening and inspecting the movement is the test that ends the question.
- Pay with a method that allows a chargeback, and put the serial number in the order notes.
- Photograph the watch on arrival and compare against the listing photos.
Photos decide most cases. Ask for close shots of the dial at 12, the date window, the crown, and the caseback. A seller who sends stock images or refuses a caseback shot is not selling a real IW329073.