Short answer
The IW371439 is an IWC Portugieser Chronograph reference. Fakes of it come in three grades: a 7750-based copy with a decorated rotor, a quartz copy, and a closer copy that mimics the caseback and dial print. The first two fail a hands-on check in under a minute. The third needs a loupe and a look at the movement.
What the reference is
IWC builds the Portugieser Chronograph around Calibre 79350. That movement is a 7750 base rated at 28,800 vph with 31 jewels and a 44-hour power reserve. The case measures 40.9 mm across and about 12.3 mm thick. The dial carries two subdials: chronograph minutes at 12 and running seconds at 6. The date sits at 3.
References inside the 3714 family share that case and movement. They differ by dial color, hand shape, strap and case metal. Confirm the dial and metal for 371439 against IWC records before you buy. Sellers label any steel Portugieser with a rare reference to lift the price.
Where replicas fail
Movement
Look through the sapphire back. Genuine 79350 has a specific rotor engraving, striped bridges and a shock absorber at the balance. Copies use a stock 7750 or a Chinese copy of it. Signs: no stripes, painted text instead of engraved text, a rotor that spins from a light flick, and a chrono seconds hand that jumps on start instead of sweeping.
Case and thickness
Most fakes run 0.5 mm to 1.5 mm thicker than 12.3 mm. A caliper settles it. Lugs on copies are often wider and the caseback sits proud of the case band.
Dial printing
Genuine dial text sits under a lacquer layer and reads sharp at 10x. Copies show dot gain on the small IWC letters. The date cut is not square. Subdial rings on fakes are stamped and show a step at the edge.
Caseback engraving
The reference number is engraved, not laser printed. Copies show a shallow etch and a wrong reference, or a missing serial between the lugs.
Checks at a desk
- Weigh the watch. A steel 3714 on a strap sits near 80 g to 90 g. Copies vary by 10 g or more either way.
- Time the chrono. Start, stop and reset should feel crisp. A soft reset points to a cheap cam.
- Listen. A 7750-based movement ticks 8 times per second. A quartz fake ticks once per second.
- Work the crown. Winding should feel smooth with light resistance. A gritty or stiff pusher is a warning.
Price reality
A genuine 3714 in steel trades used in the low to mid four figures in US dollars, depending on age, box and papers. Any listing far under that range is a replica or a watch built from mixed parts. Replica sellers price the better 7750 copies in the few hundreds.
What this guide cannot settle
Photos alone cannot confirm a movement. A seller who refuses a video of the running watch with the back open, or a photo of the movement with the rotor turned, is not selling a genuine piece. If the reference on the caseback does not match IWC records for 371439, stop.