A fake IW371756 usually shows itself in three places: the sharpness of the dial printing, the alignment of the two chronograph sub-dials, and the depth of the engraving on the caseback. Genuine IWC Portugieser chronographs are machined and finished to tight tolerances, so a replica that looks convincing at arm's length often fails under a loupe or a macro photo. The checks below work whether you are comparing a first copy watch against a genuine piece or judging photos from a seller.
What the IW371756 reference is
Reference numbers in the IW3717 block belong to the IWC Portugieser chronograph family, a line built around a clean dial, slim leaf-shaped hands, applied numerals and a two-register chronograph layout. Because the design is so simple, small errors stand out: there is no busy texture or oversized case to hide behind. That simplicity is exactly why the fake IW371756 market is worth learning before you buy.
Dial and printing checks
- Printing edges: on a genuine dial, the minute track, the brand signature and the sub-dial markings are printed with hard, clean edges. Replicas often show slight bleed or a soft, thickened look under magnification.
- Sub-dial spacing: the two registers should sit on a true vertical axis with even gaps to the centre and to the outer track. A fake frequently has one register sitting a fraction high or low.
- Applied numerals and markers: they should sit flush and reflect light evenly. Look for glue residue or a visible gap at the base.
- Hands: leaf hands should be polished on the upper surfaces with crisp, unrounded tips. Painted or roughly stamped hands are a warning sign.
- Sub-dial finish: the small concentric circles inside each register should be cut, not printed, and should catch light as you tilt the watch.
Case, crown and caseback
Run a finger along the case flanks: genuine cases are polished smoothly with an even transition into the lugs. Check the crown for a clean, deep brand engraving rather than a shallow stamp. On the back, reference and serial engravings should be cut with sharp walls and consistent depth; laser-etched replicas look grey and flat. Confirm the crystal is sapphire by its sharp reflections and cool feel, and check that the crystal sits level with the bezel line.
Movement and pusher feel
Older Portugieser chronographs use a Valjoux 7750-based calibre, while later versions move to an in-house movement, so the correct view depends on the production year. In either case, the chronograph should start crisply, stop without creep and reset to zero instantly and identically on both registers. A sluggish reset, a wobbling seconds hand or a pusher that feels mushy points to a cheaper modular movement. Where the watch has a display back, the rotor engraving, perlage and screw slots should be clean and consistent.
First copy versus low-grade replicas
Buyers searching for a fake IW371756 will see the term first copy used for the higher tier of replica, with correct case proportions, domed sapphire and a cloned or modified automatic chronograph movement. Lower grades cut corners on the dial printing and use thin plating that wears through at the lugs. Ask for macro photos of the dial, the caseback and the movement, plus a short video of the chronograph resetting.
Buying checklist
- Request photos at 3x to 5x zoom of the dial and caseback engraving.
- Confirm the sub-dials align on a vertical axis.
- Ask which movement is fitted and whether the chronograph resets to zero.
- Check pusher and crown action in a video, not just in stills.
- Remember that a replica is not a genuine IWC product and carries no brand warranty or service history.