Short answer
A fake IW371493 copies the IWC Portugieser Chronograph. The genuine watch has a 40.9 mm steel case, caliber 79350, a date window at 3 o'clock, and a rating of 30 m for water resistance. IWC keeps no public serial database, so you confirm a real one through the movement, the case finishing, and paperwork from an IWC service center.
What IW371493 refers to
IWC files the Portugieser Chronograph under the 3714 family. Each dial and case pairing gets its own reference number, and IW371493 is one of those pairings. The number covers the case, dial, hands, and strap as shipped. The 3714 series ran for more than 20 years with many combinations, so confirm the dial color and strap for IW371493 against IWC records. That step matters, because sellers mix parts from different references.
Movement: the main test
The genuine watch runs caliber 79350, a Valjoux 7750 base that IWC modifies and finishes. The counters sit at 12 and 6. Beat rate is 28,800 vph. IWC lists a power reserve near 44 hours.
Counterfeits use a Chinese 7750 copy, a Seagull ST19, or a quartz module hidden behind a decorated plate. Signals of a fake:
- A rotor that spins with no resistance.
- Bridges with rough engraving and no Geneva stripes or perlage.
- Screws with soft heads and burred slots.
- A chronograph seconds hand that stutters or fails to reset to zero.
Case, dial, and crystal
- Case sides: sharp lugs with a polished bevel and a brushed top face. Fakes show rounded lugs and a soft edge.
- Dial print: "IWC" and "Schaffhausen" sit under the 12 marker in thin, crisp type. Replica print looks heavy and the letter spacing differs.
- Markers: applied steel, polished, set with even gaps. Fakes glue them on and the gaps shift.
- Hands: leaf-shaped, with a clean edge and no burrs at the tip.
- Crystal: sapphire with an anti-reflective coating. A fake throws a strong purple or blue glare at an angle.
- Gaskets: a fake case back holds a thin or missing gasket, so 30 m of water resistance does not hold.
Check the date. It sits at 3 o'clock and centers in the window. A date that sits high, low, or off center points to a fake or a damaged movement.
Case back, serial, and papers
IWC engraves the reference and case number on the case back. The same case number appears on the movement. On a fake, the engraving is shallow, the font is wide, and the numbers on the case back and the movement do not match. An IWC service center can confirm a case number and a service history. Ask for that record in writing before you pay.
Price and seller checks
Prices for 3714-family watches on the secondary market sit in the thousands of US dollars. A listing at a few hundred dollars is a replica. Ask for three photos before purchase: the movement with the case back off, the case back engraving, and a dated receipt. A seller who ships from a stock photo and refuses a movement photo carries risk.
Where fakes fail in use
Replica chronographs lose time, the pushers feel gritty, and the crown threads wear out. Water damage follows from thin gaskets and low case back torque. A service on a fake costs more than the watch.