Short answer
"Portugieser Automatic 31" is a listing phrase, not an IWC model name. The number 31 matches the jewel count of calibre 52010, the movement inside the Portugieser Automatic ref. 5007. No IWC Portugieser Automatic has a 31 mm case. The line starts at 40.4 mm. No replica of ref. 5007 has a real 168 hour power reserve.
Genuine reference specs
- Case: 42.3 mm wide, about 14.5 mm thick
- Movement: IWC calibre 52010, automatic, Pellaton winding
- Jewels: 31
- Power reserve: 168 hours (7 days), two mainspring barrels
- Frequency: 28,800 vph, 4 Hz
- Crystal: sapphire on the dial side and the caseback
- Water resistance: 3 bar
What replica versions get wrong
The movement is the main gap. Calibre 52010 stores seven days of reserve in two barrels and winds through a Pellaton system with ceramic pawls. Replica cases hold a 40 to 48 hour Asian automatic. Builders plate the bridges, engrave text, and add blued screws to copy the look. The reserve test exposes the swap: a real 5007 runs 168 hours. A fake stops near 45.
Case height runs 12 mm to 14 mm on most fakes. The genuine mid case measures about 14.5 mm. Lug shape and crown guards change from factory to factory.
The date wheel is a common tell. The real date disc carries thin digits and a beveled aperture. Copies print thick digits and skip the bevel.
Crystal grade varies. Cheap builds use mineral glass. Mineral scratches and shows a gray cast under direct light.
Checks you can run
- Wind the watch until the crown stops. Set it dial up and note the time. Look again after 72 hours. A genuine 52010 still runs. A replica has stopped.
- Loupe the balance bridge. IWC finishes and engraves that bridge. Fakes carry laser etching on a polished plate.
- Measure thickness at the caseback with calipers. Under 14 mm points to a different movement.
- Push the crown through its positions. Calibre 52010 has a firm stop at each setting. Loose travel points to a stock Asian movement.
- Read the dial print. The logo sits under 12 with even letter spacing on the original. Copies show uneven gaps and a heavier font.
US legal status
Import of a counterfeit watch into the United States breaks 19 U.S.C. 1526. Customs and Border Protection can seize and destroy the shipment. Trafficking in counterfeit goods carries criminal penalties under 18 U.S.C. 2320: up to 10 years and a $2,000,000 fine for a first offense by an individual, and up to 20 years for a repeat offense.
What stays unknown
Factory names, batch tags, and version numbers change. Listing photos often show a different unit than the one shipped. No seller can supply a genuine calibre 52010, so the seven day reserve figure on any listing copies IWC spec. It is not a measurement.