The clearest sign of a fake IW371629 is the movement. Genuine IWC Portugieser Chronograph watches in the 3716 family run IWC's in-house caliber 69355, an automatic column-wheel chronograph with a 46-hour power reserve, and the sapphire caseback lets you read its finish and rotor engraving in seconds. Most counterfeits copy the case shape well and then fail on the movement, the subdial spacing, the dial print, and the caseback engravings.

What is the IWC Portugieser Chronograph IW371629?

The IW371629 is a reference inside IWC's Portugieser Chronograph line, a 41 mm stainless steel chronograph with a vertically stacked subdial layout at 12 and 6 o'clock.

Production examples use the in-house caliber 69355, sapphire crystal front and back, and roughly 30 m of water resistance. The case measures about 13 mm thick, so it wears slim for a chronograph.

Because it is a current reference with a strong resale market, it is copied often. The dial variation, bracelet or strap, and production year change small details, so always check the reference against the exact variant you are being offered.

How do you spot a fake IW371629?

The dial and hands

Genuine dials have applied numerals and indices with polished edges and a mirror-like top surface, plus printing so sharp you can see individual strokes under a loupe.

The standard Portugieser Chronograph dial carries no luminous material. If the hands or hour markers glow in the dark, that is a counterfeit almost every time.

Check the subdials too. On the real thing the spacing is symmetrical around the center, the hands are leaf-shaped with an even taper, and the chronograph seconds hand snaps back to zero immediately when reset.

The case and finishing

Real IWC cases show crisp transitions between brushed and polished surfaces, especially along the lugs and the bezel edge.

Fakes typically soften those lines, or polish the whole case so the brushed grain disappears. Run a fingertip along the lug edges: you should feel distinct, sharp changes in direction, not a rounded blur.

Pusher feel matters as well. Genuine pushers are firm, quiet, and consistent, while counterfeit pushers often rattle or feel gritty.

The movement

Look through the caseback and identify the caliber. The 69355 should show Geneva stripes, blued screws, a column wheel under the chronograph bridge, and a rotor engraved with the IWC Probus Scafusia medallion.

Counterfeit movements rarely reproduce this. They often use a decorated generic chronograph, a Miyota or Seagull base, or a solid caseback to hide the problem.

Test the function: start the chronograph, let it run for a few minutes, and reset it. A genuine column-wheel mechanism resets cleanly to zero every time, from any point in the hour.

Caseback, reference engraving, and paperwork

IWC engraves the reference number and case number on the caseback, and the reference is also stamped between the lugs. The engraving is fine, deep, and evenly spaced.

Counterfeit engraving usually looks shallow, laser-etched, or wrongly spaced, and the fonts are slightly off. Compare the digits side by side with official images rather than from memory.

Papers, warranty card, and box should match the reference, the movement number, and the seller's story. Mismatched numbers are the classic sign of a franken watch or a straight fake.

Strap, clasp, and presentation

Genuine leather straps for the Portugieser line are often made by Santoni, with fine stitching and soft, supple leather.

Fake straps arrive stiff, with uneven stitching, cheap lining, and buckles that feel light. On a bracelet, check the end links: they should sit flush against the case with no gaps or wobble.

Why price matters when you buy an IW371629

A genuine IW371629 sells in the four-figure range and holds value well on the secondary market, so a "new" example at a fraction of that price is not a bargain.

Sellers offering a full set with box and papers far below market, or pushing a fast, pressure-driven sale, are the two biggest red flags in the replica market.

If a deal looks too good, ask for a movement photo through the caseback and a video of the chronograph resetting. A legitimate seller will provide both.

Frequently asked questions

Does the IW371629 have a display caseback?

Yes. Genuine examples have a sapphire crystal caseback, which means you should always be able to inspect the movement before buying.

Can a counterfeit use a real IWC movement?

Rarely, but franken watches built from a genuine movement inside a counterfeit case do exist. That is why you verify the caseback engravings, the dial details, and the movement together, never one alone.

Do IWC Portugieser Chronograph hands have lume?

No. The standard dial has no luminous coating, so glowing hands or markers are a counterfeit tell.

Where should I buy a genuine IW371629?

An authorized dealer, a trusted independent watchmaker, or a reputable pre-owned platform with buyer protection and an inspection window.

Bottom line

Judge a suspected fake IW371629 on four things: the caliber 69355 behind the sapphire back, the un-lumed dial with applied markers, the sharp case finishing, and matching engravings on caseback and paperwork.

Get the watch opened by a watchmaker before money changes hands. No photograph or listing detail replaces a five-minute inspection.