Most fake IW371488 watches fail on the same four points: case thickness, dial printing, subdial spacing, and the movement visible through the display back. Check those first. A replica can copy a photograph, but it cannot copy the tolerances of a 41 mm steel case or the finish on an IWC chronograph movement.
What the reference is
The IW371488 sits in the Portugieser Chronograph family. IWC reference numbers encode the full configuration, so the same base watch appears under different numbers depending on case metal, dial color, and strap. Confirm the exact dial and strap that belongs to IW371488 on IWC's own product page before you compare anything, then hold the watch against that specification.
Case and proportions
Genuine Portugieser Chronograph cases have a slim bezel, long curved lugs, and a profile that sits low on the wrist. Fakes add material where it is cheap to add: the case runs thick, the lugs look stubby, and the bezel reads wide. Run a fingertip along the lug edges. Real ones are polished and sharp. Fakes feel rounded or unfinished at the inner corners.
Dial printing and layout
Look at the text under 12 o'clock and above 6 o'clock at an angle, not straight on. Genuine printing is crisp and slightly raised. Copies look flat, fuzzy, or unevenly spaced. On the real dial the two subdials sit close to the center line and mirror each other. On fakes one subdial often drifts toward the case edge.
Hands and subdials
- Leaf-shaped hands with clean, even edges on both faces.
- Applied numerals with polished sides, not stamped foil.
- Subdial hands that reach the printed track, not fall short of it.
- No gap between the hour hand and the dial surface.
Movement through the display back
Set the watch down and look through the sapphire back. You should see a decorated automatic chronograph movement with Geneva stripes, blued screws, and an engraved rotor. Fakes show a bare, gray, undecorated plate, a rotor with shallow etching, or a plastic spacer ring holding a smaller movement in a larger case. Press the chronograph pushers. Real ones click with resistance and the seconds hand snaps back to zero when you reset.
Caseback, engraving, and serials
Engraving on a genuine caseback cuts into the metal. It has depth and you can feel it with a fingernail. Laser-etched fakes sit flat on the surface. Match the serial on the caseback to the number on any included papers, and check that the reference number on the back matches IW371488.
Step-by-step check
- Confirm the correct dial and strap combination for IW371488 from official specification.
- Measure the case diameter and thickness with calipers.
- Inspect dial text and subdial positions under a loupe.
- Check hand shape, finish, and alignment at 12 o'clock.
- Operate the chronograph and confirm the reset returns to zero.
- Examine movement decoration through the display back.
- Feel the caseback engraving and match all serials.
- Have a watchmaker open the case and verify the calibre.
Strap, buckle, and packaging
Genuine alligator straps have irregular scale patterns. Fakes use embossed leather with repeating scales. The folding clasp should be heavy, with clean engraving on the inside face. Boxes and booklets are the easiest items to fake, so treat them as supporting evidence only.
Red flags
- A price far below the current market range for the reference.
- Seller refuses to open the caseback or allow a watchmaker inspection.
- Blurry photos, no movement shot, or stock images instead of the actual watch.
- Serial numbers that do not match between case and papers.