"Fake IW371766" usually means one of two things. Either you are looking at a replica of the IWC Portugieser Chronograph in that reference, or you own a real one and want to know what a counterfeit would look like next to it. The checks are the same either way, and the order matters. Dial first, then case, then movement, then paperwork. Most fakes fail in the first two minutes.
What the reference actually is
The IW371766 belongs to the current Portugieser Chronograph generation, a 41mm steel watch at roughly 13mm thick. Inside sits the in-house calibre 69355, a column-wheel chronograph with about 46 hours of reserve and a sapphire display back. Water resistance is 3 bar, which is a dress-watch number and not a swim number. The layout is two subdials, running seconds at 6 and chronograph minutes at 12, with a date at 3 and leaf-shaped hands.
Because references in this line differ by dial color, hand finish and strap, pull the exact variant from IWC's own catalog before you compare anything. Comparing a 371766 to a 371605 photo will send you chasing differences that are not defects.
Start with the dial, because that is where replicas leak
I look at printing under the 12 first. The "IWC" and "SCHAFFHAUSEN" lines should be razor sharp at arm's length, with even stroke weight and no ink spread. Fakes tend to look slightly bold or slightly muddy, and the spacing between the two lines drifts.
- Subdials should sit in a real recess, with a snailed texture that catches light in rings. Flat, printed subdials are an instant no.
- Applied numerals and markers have a beveled edge and a polished top face. Run a fingernail across one. Fakes are often flat plates.
- The minute track on the flange should be crisp and evenly spaced all the way around, not just where the eye lands.
- Leaf hands are curved and tapered. Cheap copies use flat stamped hands that read gray instead of bright.
- The date cut should be clean at the edges, with the disc sitting square behind it and the numerals centered.
Case, crown and pushers
The Portugieser case is mostly brushed on the flanks with polished edges, and the transition should be a hard line, not a soft blur. Thickness is the tell I trust most. Replica cases often run half a millimeter to a full millimeter thicker than the genuine 13mm because of the movement inside, and you feel it on the wrist before you see it.
Then press the pushers. A column-wheel chronograph has a light, clean, mechanical click at start and stop, and a firm snap at reset. A cam-and-lever copy feels spongy and vague. Reset should fly back to zero instantly with no creep on the chrono seconds hand.
The movement check
Turn the watch over. The 69355 shows a column wheel, striped bridges and a signed rotor. On the common 7750-based fakes the layout is different and, more useful, the small seconds at 6 is driven off the chronograph train, so it can stutter or tick unevenly. The genuine runs smooth at 28,800 vibrations per hour.
Engraving quality separates the two. Reference and serial on the genuine caseback ring are cut deep with clean shoulders. Laser-etched copies look shallow under a loupe and the font is slightly off.
Strap, clasp and small parts
Alligator grain should be irregular, with stitching that sits straight and even. Newer production uses quick-release spring bars, so check that the strap swaps without a tool if the reference calls for it. The folding clasp engraving is another place fakes get lazy: shallow lettering, wrong proportions, a pin that binds.
What a good replica gets right, and what it does not
The better fakes nail dial proportions and case shape from three feet away. They slip on thickness, hand beveling, subdial depth, pusher feel, movement finishing and engraving depth. None of those are visible in a listing photo, which is exactly why they survive.
Price is your final filter. The genuine sits in the high four figures at retail. If a seller offers a "new" one at a fraction of that, it is not a bargain, it is a replica with a story attached.
Quick checklist before money changes hands
- Confirm the exact dial variant against IWC's catalog.
- Check printing sharpness and subdial recess in raking light.
- Measure thickness with calipers if you can.
- Press both pushers and listen for the column-wheel click.
- Inspect the display back for the column wheel and rotor signature.
- Match reference and serial across caseback, warranty card and booklet.