The short answer: no one sells a fake IW371473 that behaves like the genuine watch, and the reference number on the caseback is the first thing to test. Most people who search for a fake IW371473 are really comparing a suspicious listing against a real IWC Portugieser Chronograph, so the useful question is not which counterfeit is best but how to tell the two apart. The IW371473 belongs to IWC's Portugieser Chronograph family, a line with many dial, case, and movement variants, so verification comes down to four checks: caseback engraving, dial print, movement and crown feel, and paperwork that ties a serial number to the reference.

What the reference number tells you, and what it does not

An IWC reference number identifies a specific combination of case material, dial, and strap, not just a model name. The same 37xx family includes steel, precious metal, and boutique variants, which is why the number alone never proves authenticity. Counterfeit cases often carry a plausible number stamped in the wrong place, at the wrong depth, or in the wrong typeface. Treat the number as a starting point: confirm it against IWC's own published listing for that reference, then confirm that the physical watch matches every detail of that listing.

Check 1: Caseback engraving and case geometry

Genuine IWC engraving is cut into the metal rather than printed, and the edges stay crisp under a loupe. Counterfeits tend to show shallow etching with soft borders, uneven letter spacing, or a reference number that does not match the dial configuration.

  • Pros: fast, free, and needs only a loupe or a phone macro lens.
  • Cons: top-tier counterfeits now copy engraving well, so this check alone proves nothing.

Use it when you have photos of the caseback and the seller will not send more. Mismatched engraving is enough reason to walk away.

Check 2: Dial print, hands, and crystal

The Portugieser Chronograph uses applied indices, leaf-shaped hands, and two chronograph registers. On the genuine article the printing is thin and sharp, the subdials sit level with each other, and the date font matches the reference. Fakes show flat or glued-on indices, a subdial shifted off center, and a heavier date numeral. The crystal is the other tell: the original carries an anti-reflective coating on both faces and nearly disappears against a dark dial, while many counterfeits use a single coating or none and throw a milky reflection under a lamp.

  • Pros: visible in ordinary photos and does not require opening the watch.
  • Cons: redials and service replacements complicate the comparison on older genuine examples.

Use it when you can handle the watch in person, or when the listing photos are sharp enough to zoom on the dial text.

Check 3: Movement, crown, and chronograph action

Many earlier Portugieser Chronograph examples run a Valjoux 7750-derived movement with a modular chronograph, while later versions use in-house calibres. Either way, the pushers should start and stop with a firm click, the reset should snap the hand back in one motion, and winding should feel smooth rather than gritty. Counterfeit movements are usually generic calibres with a decorated rotor and engraved bridges, and the chronograph seconds hand often stutters or hesitates before it moves.

  • Pros: mechanical behavior is hard to fake and shows up immediately by hand.
  • Cons: a convincing clone movement exists for some calibres, so a watchmaker should confirm the base.

Use it when a watchmaker can open the caseback. A short inspection costs little compared to the price of a mistake.

Check 4: Serial number, papers, and service history

IWC engraves a serial number on the case, and that number can be checked with the brand's service department or an authorized dealer. A full set means the warranty card, the caseback, and any service record agree. Counterfeit sets usually rely on a generic card, a printed serial sticker, or a number that matches nothing on the case.

  • Pros: the strongest single signal when the numbers line up and service history exists.
  • Cons: paperwork can be forged or lost, and vintage examples often have none.

Use it when a seller claims a full set. Ask for one photo showing the card and the caseback in the same frame.

Buying options, ranked by risk

Pre-owned genuine from a specialist dealer

  • Pros: real reference, traceable serial, service access, resale value.
  • Cons: highest upfront cost, and condition varies between examples.

Best for buyers who want the actual watch and plan to keep or trade it.

Trademark-free homage chronographs

  • Pros: similar two-register look, legal to buy and resell, own brand warranty.
  • Cons: different movement, no IWC markings, no collector value.

Best for people who like the design and do not care about the name on the dial.

Listings sold as replicas or fakes

  • Pros: low upfront price and a similar silhouette at arm's length.
  • Cons: counterfeit goods are illegal to import or resell in the United States, no service parts, no resale value, and a real chance of plain fraud.

Best for nobody who wants a watch that lasts. If the goal is the look, the homage route delivers the same idea without the legal exposure.

Practical verification order

  1. Photograph the caseback and compare the engraving and reference against IWC's published details.
  2. Zoom on dial text, subdial alignment, and date font.
  3. Have a watchmaker open the case and identify the movement base.
  4. Match serial numbers across case, card, and service records.
  5. Price the result against current pre-owned market listings for that reference.

If any single step fails, stop. A genuine IW371473 will pass all five.