A fake IW371416 exposes itself in four places: the caseback engraving, the case size, the movement finish, and the chronograph pusher feel. The genuine IWC Portugieser Chronograph reference IW371416 uses a 40.9 mm stainless steel case that is 12.3 mm thick, a Calibre 79350 movement, and a deeply laser-engraved reference number on the caseback rim. Copies typically miss the diameter by one to two millimeters, use a shallow stamped engraving, and hide an undecorated third-party chronograph movement under a plain rotor. Work through the checks below in order and you will separate a genuine watch from a copy in under ten minutes.
What You Need
- A 10x jeweler's loupe
- Digital calipers
- A bright, angled light source
- A soft cloth and a flat work surface
Authentication Steps
- Measure the case with calipers. The genuine case measures 40.9 mm across the bezel and 12.3 mm thick. A reading of 42 mm or a thickness over 13 mm points to a copy.
- Turn the watch over and read the caseback with the loupe. The reference number 371416 and the serial should be cut into the metal with crisp, even edges and a matte floor. Fakes show soft, rounded characters from a stamp or a laser that only burns the surface.
- Inspect the dial printing. IWC applies the "IWC SCHAFFHAUSEN" logo and the subdial text with sharp, raised edges. On copies the letters look thick, and the subdial rings often sit at slightly wrong positions.
- Check the applied indices and hands. Genuine indices sit flat against the dial with polished bevels. On fakes the indices are often glued slightly crooked and the hands look grainy under magnification.
- Press the chronograph pushers. Genuine Calibre 79350 pushers engage with a firm, short travel and a clean click. Copies feel spongy, and the reset sometimes fails to snap the hands back to zero.
- Have the caseback opened. Calibre 79350 runs at 28,800 vibrations per hour with 25 jewels. Look for circular graining, blued screws, and the IWC engraving on the rotor. A bare movement with a generic rotor and no decoration is a red flag.
- Weigh the watch in your hand. A steel Portugieser Chronograph has a substantial, even balance on the wrist. Copies built from lighter alloys feel top heavy and hollow.
- Check the sapphire crystal at an angle. The genuine crystal carries an anti-reflective coating on both faces, so the dial stays readable with almost no glare. Cheaper mineral glass throws a strong reflection.
- Match the paperwork to the watch. The serial on the warranty card, the caseback, and the movement must all agree. IWC cards carry a printed reference and serial, not a handwritten note.
Common Tells on Copies
- Caseback text with uneven spacing between characters
- A rotor engraved with IWC but with no circular graining on the bridges
- A crown that wobbles when you set the time
- Subdial hands that do not line up at the twelve o'clock position after a reset
- Lume that glows a different color on the hands than on the indices
Confirming the Result
If two or more checks fail, treat the watch as a copy and walk away. If the checks are close, take the watch to an IWC boutique or an authorized service center. A watchmaker can open the case in minutes and confirm the movement and serial. A paper trail from a private seller is not proof on its own, so always match the serial to the case before you pay.