Quick Answer
A fake IWC Portugieser Chronograph IW371435 fails in four places: the movement, the subdial spacing, the caseback engraving, and the strap hardware. Genuine 3714-family watches run a modified Valjoux 7750 (calibre 79350) with finished bridges and an engraved IWC rotor. Copies run a stock 7750 or a cheap chronograph module under a decorative plate. Check the movement first, then the dial layout, then the case.
What the Reference Should Look Like
The IW371435 belongs to the Portugieser Chronograph 3714 family. Steel case, about 40.9 mm across, roughly 12.3 mm thick, 20 mm lugs, sapphire crystal with coating on both faces, and a screw-in display back. The dial carries two subdials on a vertical axis: small seconds at 6 o'clock, elapsed chronograph minutes at 12. The crown sits at 3 o'clock and is signed. Water resistance is rated to 3 bar.
If the watch in front of you has a date window, it is either a later 3716 reference or a copy built on a different base. The classic 3714 layout keeps the dial clean with two subdials and no date.
Before You Start
- A jeweler's loupe or a phone macro lens
- A bright light you can angle across the dial
- Calipers if you own a pair
- The seller's photos at full resolution, unedited
How to Check an IW371435 Step by Step
- Measure the case with calipers. Genuine 3714 cases read 40.9 mm across the bezel and close to 12.3 mm thick. Copies land between 40.0 and 42.5 mm and sit thicker than 13 mm.
- Turn the watch over and study the movement through the display back. You want a Valjoux 7750 base, a signed rotor, blued screws, and stripes cut into the metal.
- Run the chronograph. Start it, let it run two minutes, then reset it. Pushers on a real 79350 feel firm with short travel and a crisp snap on reset.
- Check the subdial positions. Small seconds sit at 6 and chrono minutes at 12, both dead on the vertical center line.
- Look at the subdial hands. They should be thin, straight, and reach the printed track without overhang.
- Inspect the printing with magnification. The IWC and Schaffhausen text is crisp with sharp serifs and even letter spacing.
- Examine the caseback engraving. Reference numbers and the Probus Scafusia script are cut into the steel, so a fingernail catches the edges.
- Check the crown. It should be signed and screw down on smooth threads.
- Inspect the crystal at an angle. Sapphire with anti-reflective coating throws a faint blue or purple sheen. Mineral glass shows no coating.
- Flex the strap and study the buckle. Real alligator has irregular scales that taper toward the lugs. Embossed cowhide repeats the same pattern. The buckle should be signed and heavy for its size.
- Weigh the watch in your hand. Steel 3714 references feel dense and balanced. Copies with plated or hollow cases feel light.
Where Copies Fail Most Often
- Rotor decoration that is printed instead of engraved
- Subdials set off center or fitted with the wrong hand shape
- Shallow caseback engraving with rounded edges
- Pushers that rattle when you shake the watch
- Case thickness above 13 mm
- Strap stitching in a uniform machine pattern that real alligator cannot produce
Buying Online
Ask for a video of the chronograph starting and resetting. Request a macro shot of the caseback and the movement. If the seller refuses either one, walk away. Match the reference number on the papers against the number engraved on the caseback, and confirm the serial appears in the same font as factory examples.