The short answer
"Fake IW371632" almost always means a replica of the IWC Portugieser Chronograph. Reference 3716 is the 41mm steel version with the two-register dial, small seconds at 6 o'clock, chronograph minutes at 12, and the date at 3. Dial colors and strap choices vary across the family, but the case, layout and movement stay close to the same. So when I look at a fake 371632, I'm judging the whole 3716 series, because the same parts turn up across the range.
Quick verdict: the good replicas nail the 41mm case, the bi-compax dial and the date placement, and they run a mechanical chronograph. The bad ones get the subdial spacing wrong, print the date in the wrong typeface, and hide a rough movement behind a display back.
The real watch, in plain numbers
IWC builds the current Portugieser Chronograph around a 41mm stainless steel case that sits about 13mm tall, with sapphire front and back, 20mm lugs, and 30m of water resistance. Inside is the in-house calibre 69355, automatic, roughly 46 hours of reserve. The generation before it, reference 3714 with the ETA/Valjoux base calibre 79350, is what most older replicas copy.
That 30m rating matters. It is splash resistance, nothing more, and plenty of replicas claim 50m and then fog up after a hand wash.
What separates a good fake from a bad one
- Dial layout. Subdial centers, the gap between them, the weight of the printing. Applied numerals should sit proud with sharp edges, not printed flat.
- Date window. Aperture shape, position, and the font of the numerals. This is the single easiest tell in photos.
- Hands. Leaf shape and length. Blued steel looks different from painted blue under a loupe.
- Movement. A decorated 7750 clone, a copy of the 69355, or quartz. Through the sapphire back you can see rotor engraving, perlage and striping. Quartz is an instant no.
- Case finishing. Brushed flanks, polished bezel, crisp lug edges. Soft, rounded edges read as cheap from a foot away.
- Crystal. The real sapphire carries anti-reflective coating on both faces. Many fakes coat one side and look flat and gray.
- Thickness. Replicas often run 1 to 2mm thicker than the real thing. It shows on the wrist and under a cuff.
Checks I run before paying
- Ask for a movement photo and a video showing the seconds hand sweep and the chrono snapping back to zero.
- Request dial macros. Look at the brand printing and the minute track.
- Confirm the caseback engraving has depth, not laser-flat text.
- Ask for a caliper shot of the case thickness.
- Check what strap is fitted. The genuine watch ships on alligator with a steel pin buckle or folding clasp.
Fit and daily wear
A 41mm Portugieser wears large because the dial is nearly all crystal and the bezel is thin. On a 6.5 inch wrist it dominates; on 7.5 inches it sits right. The 20mm lug width means straps are easy to swap, and a decent leather strap does more for the look than any other upgrade.
Water, service and honesty
Treat any replica as splash resistant. No shower, no pool, no swimming. Mechanical chronographs need servicing every few years, and most replica-friendly watchmakers will work on a 7750 base without much fuss.
One last thing. A replica is a replica. Wear it because you like the look, not to pass it off. Selling any watch as genuine when it is not is fraud in most places, and that is a line worth staying well clear of.