A fake IW371645 usually reveals itself in four places: the subdial layout, the dial printing, the caseback, and the feel of the chronograph pushers. The genuine IWC Portugieser Chronograph has crisp controls and precise finishing, while most replica IW371645 watches use a stock or decorated 7750-based movement that feels rough and can place the running seconds in the wrong position.
Start with the dial
The dial is the fastest place to separate a genuine Portugieser from a replica. Use a loupe or a phone macro shot and compare every detail with photos of the exact reference.
- Subdial layout: the genuine Portugieser Chronograph places running seconds at 6 and the chronograph minute counter at 12. Many budget replicas keep the stock 7750 layout with running seconds at 9, which is an immediate fail.
- Printing: check the IWC logo, the Portugieser name, and the minute track. Replica printing often looks thick, fuzzy, or uneven under magnification.
- Hands: the leaf-shaped hands should be polished, faceted, and cleanly finished. Replica hands often look flat or show burrs along the edges.
- Date window: the date at 3 should be cleanly cut with the correct font and good magnification. A misaligned date wheel or a sloppy aperture is a common replica tell.
Case, crown, and pushers
The Portugieser Chronograph case is roughly 41 mm wide with a slim bezel and curved lugs. A fake IW371645 often has lugs that are too thick, a bezel that sits too tall, or a crown that does not sit flush against the case. Run a finger over the case edges; genuine finishing feels smooth and consistent, while replica edges can feel sharp or uneven. The chronograph pushers should start, stop, and reset with a firm, clean click. A spongy or grinding pusher is a warning sign.
Caseback and movement
On references with a sapphire display back, inspect the movement finishing and engraving. The caliber text should be sharp and correctly placed, and the rotor finish should match reference photos. Replicas often use a decorative plate over a stock movement, so the gear train and finishing look wrong when compared side by side. If the caseback is solid, check the engraving depth, font, and serial spacing. Shallow laser etching is easier to fake than crisp, deep engraving.
Weight, bracelet, and clasp
A replica IW371645 often feels lighter or heavier than expected because the case and bracelet are not made to the same tolerances. On steel bracelet versions, check the end links for a tight fit and the clasp for clean engraving. The bracelet should articulate smoothly without rattles or stiff links.
Paperwork, price, and source
Paperwork is easy to fake, so do not treat a box and card as proof. Verify the serial number, reference number, and date of purchase with the seller, and ask for close-up photos taken in daylight. A price that is far below the normal pre-owned range for an IW371645 is a warning, not a bargain. Buy from a seller with a clear return policy and a history of selling high-end watches.
Quick checklist before you buy
- Confirm the subdial layout matches the genuine reference.
- Inspect dial printing and hand finishing under magnification.
- Check case edges, crown fit, and pusher feel.
- Compare caseback engraving and movement finishing with reference photos.
- Verify the serial and reference numbers, and get the claim in writing.