A fake IW371646 is a counterfeit copy of the IWC Portugieser Chronograph that borrows the reference number but not the materials, movement, or finishing of the genuine watch. On most copies the tells show up in the caseback engraving, the dial printing, the pusher action, and the movement visible through the display back. Knowing where the reference sits in the IWC lineup makes the fakes easier to read.
What the IW371646 reference actually is
The IW371646 belongs to the IW3716 family of Portugieser Chronographs, a 41 mm stainless steel line with a narrow bezel, a clean dial, two subdials at 12 and 6, and an in-house automatic chronograph movement. The genuine watch has a sapphire crystal on both sides, a signed crown, and a caseback with crisp, deep engraving of the reference, the serial, and the model name.
Because that layout is minimal, a counterfeit does not have to fake much decoration to look convincing in a photo. That is exactly why this reference is copied often and why a few structural checks matter more than a first impression.
Tells that separate a fake IW371646 from the real thing
- Caseback engraving. Genuine engraving is sharp with even depth. Copies look shallow, sandblasted, or slightly blurred at the edges, and reference or serial numbers sometimes repeat across listings.
- Dial printing. Look at the brand name, the subdial rings, and the minute track. On fakes, letters thicken at the curves, subdial rings sit off center, and the date window is often cut slightly crooked.
- Pushers and crown. Genuine chronograph pushers have a short, clean travel and a firm reset. Copies feel spongy, grind, or need a hard push to snap back to zero.
- Movement. The real watch uses an in-house automatic chronograph calibre with a column wheel, and the finishing, rotor engraving, and balance area are tidy under the sapphire back. Counterfeits usually hide a generic or cloned movement with rough edges, wrong jewel counts, or a rotor text that does not match the reference.
- Case and bracelet finishing. Brushed and polished surfaces should meet on a crisp line. Fakes show rounded transitions and uneven polish along the lugs.
- Crystal and hands. Genuine sapphire has almost no distortion at an angle. Copies show haze, a strong blue tint, or a domed look that does not belong on this reference.
Why the reference number alone proves nothing
Replica sellers commonly print a real reference number on a card, a hang tag, or a web listing. The number is public information, so it is easy to copy. A genuine IW371646 is verified through the watch itself: the movement, the engraving quality, the feel of the winding and chronograph action, and the service history.
Listings that misspell or reformat the reference are another warning sign. Real production records and dealer paperwork use the same format across every document.
How to check before you buy
- Ask for sharp photos of the caseback, the movement through the display back, and the clasp engraving.
- Compare those photos with product images published by the brand for the same reference.
- Request a service record or an authentication report from a qualified watchmaker, not from the seller.
- Price the watch against the current secondhand market. A price that sits far below the normal range almost always points to a fake IW371646 or a watch with a swapped movement.
Legal and ownership notes
Selling counterfeit watches is illegal in the United States and in most other markets, and brands will not service or supply parts for a fake. If you already own a copy, an independent watchmaker can confirm what is inside, but the watch has no factory support and no resale value as an IWC.
If your goal is the look of the Portugieser Chronograph, the safer route is a genuine pre-owned example with papers, or a different brand in the same style bracket. Either option keeps the reference number meaningful.