The short answer

A "fake IW371433" is a counterfeit of the IWC Portugieser Chronograph, the steel two register chronograph from the 3714 reference family. The design looks simple, which is exactly why it gets copied so often, and also why a bad copy is easy to catch. The tells live in four places: the movement, the subdial spacing, the dial printing, and the caseback engraving. Everything else is noise until you have checked those.

One warning before the details. Customs in the US and most of Europe seizes counterfeit watches on sight, and no IWC service centre will touch one. If you are buying, the reference number on a listing is not proof of anything. Anyone can type 371433 into a photo caption.

What the reference actually is

The 3714 family is the Portugieser Chronograph: a 40.9 to 41 mm steel case, a thin bezel, leaf shaped hands, applied numerals at 12 and 6, and two subdials stacked vertically, the 30 minute counter up top and running seconds below. The strap is usually alligator with a pin or folding buckle. Whether a given reference carries a date aperture at 3 is worth confirming against IWC's own spec sheet, because replicas regularly add a feature the original never had, or drop one it did.

Movement depends on the production year. Earlier 3714 pieces ran the 79350, a heavily reworked Valjoux 7750. Later ones moved to the in house 69355 with a column wheel. That split matters a lot when you are trying to date a watch, or expose a fake.

Where replicas fall apart

The movement and the pushers

Start the chronograph, then stop it and reset it a few times. A 7750 based original feels crisp on the start and stop, with a firm, short reset. Most fakes use a cheap 7750 clone or a modular quartz hybrid, and the pushers feel spongy or gritty. Wind it slowly and listen. The rotor on a cheap 7750 clone wobbles noticeably on the wrist, a spinning sensation the real thing does not produce. If the watch is selling with a display back, look at the finishing on the bridges and the shape of the column wheel or cam. Blurred brushing and stamped rather than chamfered edges are the usual giveaways.

Subdial spacing and hands

On the genuine dial the two subdials sit close to the centre and stay symmetrical with the 12 and 6 numerals. Fakes based on a generic 7750 clone often push the subdials slightly apart, or place the 30 minute counter a hair left of centre. Hold a straight edge or a phone photo across the dial and check. Hands are another tell. The genuine leaf hands are polished, with a clean taper from base to tip. Fakes tend to be a touch too flat, too wide near the pinion, or lightly chromed instead of polished steel.

Dial printing and numerals

Get close with a loupe or a phone macro shot. On the original, the IWC signature and SCHAFFHAUSEN are crisp, evenly spaced, and sit level with the horizon of the dial. Fake printing looks heavier, sometimes with a faint double edge from a pad printed transfer. Applied numerals on the genuine watch have sharp, mirror polished facets. On fakes the facets are shallow or the edges rounded. Printed minute tracks should be thin and dead straight all the way around.

Case, engraving and caseback

Reference and serial engraving between the lugs is a fast test. Genuine engraving is shallow, sharp and even, done with a fine tool. Fake engraving is often laser etched, so it looks grey and slightly frosted inside the cuts, with the wrong font weight. On the caseback, check the letter spacing of the brand name and the depth of the sapphire. A fake crystal usually has weak or uneven anti reflective coating, and the dial looks washed out at an angle rather than inky black.

Strap, buckle and packaging

Genuine alligator has irregular scale size and a soft, matte finish that ages. Fakes use embossed calf that looks too uniform and too glossy. Buckle engravings on fakes are typically deeper and rounder than the real thing. Boxes are the easiest part of a counterfeit package to fake, so treat a full set as a small bonus, never as proof.

Price reality

If a 371433 is offered at a fraction of the used market price, it is not a bargain, it is a counterfeit. There is no wholesale channel for new old stock IWC chronographs at 90 percent off. If you want the look without the risk, buy a verified pre owned example from a dealer who will open the caseback for you, or look at an honest microbrand chronograph with the same layout.