The replica IW371620 you'll see listed online is a copy of IWC's 41 mm Portugieser Chronograph in stainless steel. The genuine watch runs IWC's in-house 69355 automatic chronograph, has two subdials at 12 and 6, no date window, and a 46-hour power reserve. The better copies get the case size, the subdial placement, and the dial texture close. Cheap ones can't, and the reason is almost always the movement underneath.
What the genuine IW371620 is
- 41 mm stainless steel case, 13.1 mm thick, 20 mm lugs
- In-house calibre 69355, automatic, 28,800 vph, 46 hours of reserve
- 30 m water resistance (3 bar), sapphire front and back
- 30-minute counter at 12, small seconds at 6, no date
- Feuille hands, applied numerals, finely grained lacquer dial
IWC builds several dial and strap versions inside the 3716 family, so compare a copy against the exact reference and dial color you're buying, not a stock photo of a different variant. The reference number plus the dial color is the only clean comparison.
Why this reference is hard to copy well
The layout is the problem. The 69355 puts the chronograph counter at 12 and the running seconds at 6. Most affordable mechanical chronographs use a Valjoux 7750 architecture, which carries subdials at 12, 9 and 6. To fake the IWC look, a factory has to blank one out, build a module, or accept a layout that's plainly wrong. That's where the tells live.
What I check first
Case first. 41 mm across, 13.1 mm thick. Anything visibly fatter than 13.5 mm and the caseback starts to bulge past the lugs, which shows on the wrist and in photos. Then I look at the gap between the two subdials. On the real dial there's a clear field of grainé between them, with the feuille hands sitting proud. Copies tend to crowd the subdials together or shorten the hands.
Next, the date. There is no date on this reference. I have seen copies where the movement still carries a date wheel and the factory simply paints over it, and you can catch a faint shadow or a raised patch at 3.
Then the pushers. Press them. A good cam or column wheel chronograph starts crisp and the reset snaps back to zero in one hit. A tired 7750 clunks, and the counter sometimes settles a hair off zero.
Movement reality check
Ask for an open caseback photo. Genuine IWC finishing reads easily: Geneva stripes, circular graining, a signed skeleton rotor with the medallion. Replicas usually show a decorated plate and a laser-etched logo, and the regulation system rarely matches. If the seller won't send a movement photo, that's your answer.
Bracelet, strap, and hardware
If your reference comes on the steel bracelet, endlink fit is the tell. Real IWC endlinks sit flush with the lugs, no step, no rattle. Copies often show a small ledge or a loose joint. On leather versions, check the buckle: the stamping is deep and centered, and the pin should be polished on every face.
Photos to ask for
- Straight-on dial shot in daylight, no filter.
- Case profile at lug level so thickness can be measured.
- Open caseback with the movement visible.
- A short video of the chrono start, stop and reset.
- Macro of the crown and the caseback engraving.
Price tiers and what you get
Under $150, expect quartz or a basic 7750 with a wrong subdial and a hollow bracelet. Around $250 to $450, you're in the range where case dimensions and dial printing are usually right. Above that you're paying for better movement finishing, real dial texture, and closer hand geometry. Past a point you're paying for details only you will ever see.
Keep it honest with yourself
A good copy of this reference will fool someone across a table. It won't fool a watchmaker with a loupe, and it shouldn't. Servicing is the other issue: most replica chronographs run on movements local watchmakers won't touch, so plan on replacement rather than repair. And importing counterfeit goods into the US is illegal, with shipments subject to seizure at the border.