A fake IW371421 is a counterfeit of the IWC Portugieser Chronograph, a 40.9 mm stainless steel watch with two subdials and an IWC-modified Valjoux 7750 inside. Genuine watches have a signed movement, crisp dial printing, and a case back serial that matches IWC service records. Fakes break down at one of those three points.

Below: what the reference number means, the checks that catch counterfeits, and what replica grade labels actually describe.

What Is the IWC Reference IW371421?

IW371421 belongs to the IWC Portugieser Chronograph family, a line IWC has built since the late 1990s. The watch uses a round 40.9 mm steel case, a sapphire crystal, and a two-register chronograph layout with chronograph minutes at 12 o'clock and running seconds at 6.

Inside sits IWC calibre 79350, a Valjoux 7750 base that IWC rebuilt with its own rotor, finishing, and chronograph module. Water resistance is 30 meters, which suits a dress watch and nothing more.

IWC has made many dial and strap combinations under the IW3714xx umbrella, so confirm the dial color, hands, and strap fitted to your exact number before you judge a watch.

How Do You Spot a Fake IW371421?

Four checks catch most counterfeits. Run them in this order.

1. The movement and the subdial layout

Start the chronograph and watch both subdials. On a real IW371421 the running seconds sit at 6 o'clock and the chronograph minutes at 12. A stock Valjoux 7750 puts small seconds at 9 o'clock, so a fake built on an unmodified 7750 has the wrong layout or a transfer plate that raises the hands.

Look through the case back. The rotor should carry IWC markings, and the bridges should show Geneva stripes with perlage on the base plate. A quartz copy gives the game away with a ticking seconds hand instead of a sweep.

2. Dial printing and hands

• Text weight: "IWC Schaffhausen" and "Portugieser" should look clean with no blur or double edges.
• Subdial rings: even spacing, sharp concentric circles, and no gaps at the crosshair.
• Hands: feuille shape, polished flanks, and a fine sweep at the tip. Painted or stamped hands look flat under a loupe.
• Numerals: applied and level with the dial. Loose or crooked markers point to a rebuilt dial.

3. Case, pushers, and crown

The pushers sit flush with the case band and press with a firm click at the start and a softer stop. Cheap pushers rattle and feel gritty in the hand. Brushed surfaces should run straight across the lugs, with polished bevels that catch light in one line.

4. Case back, serial, and paperwork

The case back carries the reference number and an eight-digit serial. Those two numbers should match the dial configuration and the papers. An IWC boutique or service center can confirm a serial from its records, which is the only check that settles the question.

A real box, warranty card, and manual prove nothing on their own. Fakers copy packaging with ease, so treat paperwork as a hint, not proof.

What Do Replica Grade Labels Mean?

Sellers split fakes into tiers, and the label tells you which movement sits inside.

• Quartz copies: battery movement, ticking seconds, subdials that do not function.
• Mid-tier automatic: Asian 7750 base with a working chronograph and the wrong subdial layout on many builds.
• "Super clone" or "1:1" claims: decorated Asian movement with closer case work, still not an IWC calibre 79350.

Price tracks the movement. A decorated automatic costs more than a quartz copy, and the gap between the middle tier and the top tier stays small because both share the same base.

No fake carries IWC's movement architecture, its service network, or its parts supply. That matters if you plan to keep the watch running for years.

Is Buying a Fake IW371421 Legal?

In the United States, selling or trafficking in counterfeit goods is illegal under federal trademark law, and US Customs can seize counterfeit imports. Buying for personal use sits in a gray zone that varies by state and by border. This is general information, not legal advice.

FAQ

How can I tell if an IW371421 is fake from photos?

Ask for a movement shot, a case back shot, and a dial macro. Blur, uneven print, and a stock 7750 subdial layout all show up in photos. A seller who refuses a movement photo is telling you something.

Does a fake IW371421 keep good time?

An automatic fake with an Asian 7750 can hold a few seconds a day after regulation. Quartz copies keep better time than the genuine watch. Neither matches IWC finishing or long-term service support.

Do fake IW371421 watches have serial numbers?

Yes. Most carry an engraved reference and serial, and many repeat the same serial across a production run. Duplicate serials and serials that do not match the dial variant are common.

Where can I check a real IW371421 serial?

Send the number to an IWC boutique or authorized service center. They can confirm the reference and production details. Auction houses and dealers with IWC accounts can do the same.

The Short Version

Check the subdial layout first, then the movement, then the dial print, then the serial. A genuine IW371421 passes all four. Anything that fails one check is not worth your money at any price.