How to Spot a Fake IW371778
A fake IW371778 fails on four checks: case size, dial printing, caseback engraving, and movement finish. Inspect those four points first. If a seller blocks any of them, end the deal.
The IW371778 sits in the IWC Portugieser Chronograph family, a steel case with a chronograph layout. Replica makers copy the silhouette well from three feet away. They copy the small details poorly. Your job is to spend your time on the small details.
What You Need
- A 10x jeweler's loupe
- Digital calipers that read to 0.01 mm
- A digital scale that reads in grams
- Daylight or a 5000K lamp
- A phone with a macro lens
- The official IWC reference data for this watch
Steps
- Photograph the watch in daylight from the front, the back, and both sides. Use macro mode and keep the lens square to the surface.
- Measure the case diameter with the calipers at the widest point, then measure the thickness from caseback to crystal. Compare both numbers to the factory figures.
- Weigh the watch on the scale. A steel Portugieser Chronograph lands in a narrow band. Fakes built on thin brass or aluminum cases miss it.
- Look at the dial printing through the loupe. Check the letter spacing in the brand name, the thickness of the stroke, and the crispness of the minutes track.
- Examine the subdial hands at the center pinion. Genuine hands sit flush and level. Fake hands often sit high, tilt, or show a rough cut edge.
- Check the date window for a beveled frame and a centered numeral. A printed or sticker date wheel is a strong fake signal.
- Turn the crown between your fingers. Genuine crowns turn with light, even resistance and swap positions with a firm click.
- Press each chronograph pusher. Real pushers travel a short, clean distance and reset the hands to zero every time.
- Inspect the caseback engraving under the loupe. Genuine engraving has sharp, deep walls with no burrs. Laser-etched or stamped fakes look shallow and soft.
- Read the reference and serial number on the caseback, then check both against the IWC record for this model.
- Remove the strap and look at the lug holes and spring bars. Genuine lugs are polished inside and out, with no tool marks.
- Look at the movement through the display back, or have a watchmaker open a solid back. Check the rotor engraving, jewel settings, and screw heads.
- Verify the strap, buckle, and spring bars. Compare stitching, leather grain, and the shape of the buckle tongue to the factory part.
Red Flags
- Case diameter off by 0.5 mm or more
- Dial text that blurs or bleeds under 10x magnification
- Caseback text with rounded edges or uneven depth
- A rotor that spins with a tinny rattle instead of a smooth sweep
- A serial number that returns no record or points to another reference
- A seller who refuses an in-person inspection or a watchmaker's opinion
Verify Before You Pay
Send the caseback photo and serial to IWC service and ask for a service history check. A watchmaker can open the case in minutes and confirm the movement, the dial feet, and the case construction. That fee is small next to the price of a fake. When the checks pass, buy. When any single check fails, walk away.