A fake IW371631 is a counterfeit of the IWC Portugieser Chronograph 41, a 41 mm stainless steel automatic chronograph with twin subdials and a date at 3 o'clock. The fastest way to expose one is the movement, not the dial: the genuine watch runs IWC calibre 69355 with a 46-hour power reserve and striped finishing visible through a sapphire caseback, while replica cases hide a generic 7750-based automatic with a rough rotor and flat, unpolished bridges. Case thickness, crown engraving and paperwork are the secondary checks that confirm what the movement already told you.

What is the IW371631?

The IW371631 sits in the Portugieser Chronograph 41 family, a line IWC refreshed in 2020 with a new automatic chronograph movement replacing the older modular calibre. The case is stainless steel at roughly 41 mm across and about 13 mm thick, with sapphire crystal front and back and 30 m of water resistance. The dial carries a chronograph minutes counter at 12, small seconds at 6, leaf-shaped hands and applied Arabic numerals.

How do you spot a fake IW371631?

Start with the movement and caseback

• Genuine IWC calibre 69355 shows striping, blued screws, a skeletonised rotor and crisp engraving.
• Replicas show dull rotor engraving, missing perlage and a rotor that rattles when the watch is shaken.
• The caseback reference and serial are laser sharp on the original and shallow or doubled on most fakes.

Then check the dial and hands

• Genuine printed text has a raised, matte ink; replicas look flat or slightly bold.
• Applied numerals on the original are polished on top and angled on the sides.
• Chronograph hands should reach the track exactly and reset to 12 without drift.

Finish with case, crown and crystal

The original has a broad polished bezel that flows into a brushed case flank, and the crown engraving sits centred with clean edges. Genuine double-sided anti-reflective coating makes the sapphire nearly disappear, while fakes reflect strongly or show a purple haze. Pushers on a real IWC travel with an even spring and a soft stop.

What do Super Clone IW371631 replicas get right?

High-end replicas copy the 41 mm case profile, the subdial layout and the applied numerals well enough to pass a glance across a table. They fail at depth. The chronograph pushers feel gritty, the seconds hand stutters at reset, and the watch is often half a millimetre thicker than the original. Weight and balance give it away in the hand long before a loupe does.

How much should a fake IW371631 cost?

Replica pricing for this reference usually lands between $300 and $800 depending on movement grade and finishing level. A genuine Portugieser Chronograph 41 sells new for around $8,000 in steel and trades in the high four figures used. Any "genuine" watch offered far below market, without matching reference and serial paperwork, should be treated as counterfeit.

Frequently asked questions

Does a fake IW371631 have a working chronograph?

Most do, because a 7750-based automatic drives the counters. The start, stop and reset feel soft, and the minute counter can creep after repeated use. Genuine calibre 69355 pushers click with a defined snap and the sweep hand lands on 12.

Is a fake IW371631 waterproof?

Assume it is not. Replicas rarely hold more than splash resistance, and the case gaskets are not built to the standard IWC specifies. Never swim with a replica, and have any watch pressure tested before trusting it near water.

Can a watchmaker tell a fake IW371631 instantly?

With the caseback open, yes, the finishing on a 69355 separates itself from any clone in seconds. Without opening the watch, an experienced dealer checks crystal reflections, crown engraving and dial print weight first.

What paperwork comes with a real IW371631?

Genuine IWC watches ship with a warranty card or digital registration, a manual and a numbered guarantee booklet tied to the case serial. The reference and serial engraved on the caseback should match that paperwork exactly. Replica batches often reuse one serial across many watches, which makes the mismatch easy to catch.

Bottom line on the fake IW371631

Buy the seller, not the watch. A fake IW371631 can survive a photograph, but it cannot survive a loupe on the dial print, a shake of the rotor or a paperwork cross-check against the caseback engraving.