A fake IW329170 is a counterfeit copy of the IWC Portugieser Automatic 42, and the quickest way to expose one is the display caseback: a genuine watch shows a decorated in-house calibre with Pellaton winding, blued screws and a reference engraving that matches the papers, while most fakes show a generic third-party movement with plain finishing or a glued-on rotor plate. Everything else, from dial printing to crown engraving, is a secondary check that confirms what the movement already tells you.
What does “fake IW329170” actually mean?
The string comes from the IWC reference system, where Portugieser Automatic 42 models sit in the IW3291 family and the last digits mark dial, case metal and strap variants. Searchers use the phrase to mean a replica of that 42mm Portugieser, not a specific single reference. Because the reference digits vary by variant, a listing that quotes one fixed number for every colorway is already a warning sign.
How do you tell a fake IWC Portugieser from a genuine one?
Work from the back of the watch forward, then finish with the paperwork. Fakes usually fail on the movement first and the dial second.
Caseback and reference engraving
- Genuine engraving is laser-sharp with even depth, and the full reference reads in the IW3291xx format with matching serials on the caseback and movement.
- Fake engraving looks shallow, fuzzy at the edges, or uses a reference number that does not match the dial configuration shown.
- Caseback threads and gasket seating on genuine watches are clean and machined, not rough or over-polished.
Movement through the sapphire back
A genuine Portugieser Automatic 42 carries an in-house automatic calibre with Pellaton winding, roughly 60 hours of reserve and striped or grained bridges. Replicas typically hide a mass-produced Asian automatic under a decorative plate. Ask for a clear macro photo of the balance, the rotor engraving and the jewel settings before you commit.
Dial, hands and crown
Genuine dials use applied numerals with polished facets, a crisp railway minute track and leaf-shaped hands with a clean, unbroken curve. Fakes show soft printing, flat or milky dial finish, hands with visible burrs and a crown engraving that is stamped rather than crisply cut. Weight and case thickness also run light or thick on copies.
What should a genuine IW3291 spec sheet show?
- Case size around 42mm with sapphire crystal on both sides and screw-in or push-fit caseback as per variant.
- In-house automatic movement, Pellaton winding system, approximately 60-hour power reserve, 28,800 vibrations per hour.
- Small seconds display and applied Arabic numerals depending on the exact reference.
- Water resistance rated at 3 bar, which is splash resistance, not swimming.
- Full set: box, guarantee card with dated retailer stamp, and matching serial numbers.
How should you vet a seller before buying a replica?
Request dated macro photos of the dial, caseback and movement, plus a short video of the seconds hand sweeping and the crown operating. Confirm the return window in writing and pay with a method that offers buyer protection. A seller who cannot supply movement shots or refuses returns is not worth the risk at any price.
Why does price alone not prove authenticity?
Genuine steel Portugieser Automatic 42 watches trade in the high four to low five figures in US dollars depending on metal and condition, so a “too good” offer is a red flag rather than proof. Replica pricing sits far lower and varies with movement quality. Judge the watch on the movement and the paperwork, not on the number in the listing title.