A fake IW371789 usually gives itself away in three places: the dial printing and sub-dial spacing, the finishing on the case and lugs, and the way the chronograph pushers feel. There is rarely one single obvious flaw — the tell is a stack of small details that do not match how IWC finishes a Portugieser Chronograph. Before you judge any watch, confirm which reference and caliber the seller claims it is, then compare that against the specification on IWC's own site.

Start with the reference, not the dial

Reference numbers are the cheapest thing for a counterfeiter to copy and the easiest thing for a buyer to skip. Ask for a clear macro photo of the engraving between the lugs and the model reference on the caseback, then check that it matches the dial configuration and case metal the seller describes. A "fake iw371789" is often a generic Portugieser-style case dressed up with whatever reference number sells best, so mismatches between the number, the dial, and the caliber are common.

IWC offers an archive extract service that confirms production details for a specific watch, which is the cleanest way to validate an expensive private sale. If a seller refuses to share serial photos or pushes back on an archive request, treat that as an answer in itself.

Dial and hands: where replicas slip

  • Printing crispness. Genuine dial text sits flat and sharp under a loupe, with even spacing and no ink bleed. Replica printing often looks slightly thick or fuzzy at the edges.
  • Sub-dial positioning. On a Portugieser Chronograph the two sub-dials sit at 12 and 6, and their spacing relative to the center hand and the date window is fixed. Replicas frequently place them a fraction off, or use a dial blank borrowed from a different reference.
  • Applied numerals and indices. Look for consistent height, polished bevels, and no glue residue at the base. Replica markers are often flatter and slightly uneven in height from one side to the other.
  • Hand finish. Leaf-style hands should be cleanly faceted, with a crisp center line and no burrs where the hand meets the pinion.
  • Date window. The cutout should be sharp-cornered and centered in the aperture, with a date disc that sits flush rather than recessed.

Case, crystal, and caseback

Case finishing is where the price gap shows. Genuine Portugieser cases have a defined transition between brushed and polished surfaces, lugs that taper evenly, and a bezel that catches light in one continuous line. On replicas, the brushing often runs in the wrong direction, the lug edges feel soft, and the polished flanks show ripples under raking light.

Crystal quality matters too. Anti-reflective coating should make the dial readable at an angle without a heavy blue or purple cast. Check the caseback engraving depth and font, and confirm whether your reference is supposed to have a solid or exhibition back — a see-through back on a model that should be closed is a quick disqualifier.

Chronograph feel and movement

Press the pushers. A genuine column-wheel chronograph starts with a light, clean click and the seconds hand jumps without hesitation; the reset should snap back to zero instantly and identically every time. Replica movements often feel mushy, need a firmer push, or let the hand drift slightly off zero after reset.

If the watch has an exhibition back, compare the movement architecture against reference photos of the caliber that model should use — bridge shapes, jewel count, engraving style, and rotor decoration are hard to fake convincingly. Listen as well: a rough or rattly winding feel is a bad sign on any watch at this price.

Papers, price, and seller behavior

  • A price far below the current secondary market for the reference, with no explanation, is the oldest red flag in the hobby.
  • Stock photos instead of dated, in-hand images of the actual watch.
  • Box and papers that look new while the watch shows wear, or paperwork with mismatched serials.
  • Sellers who will not do a video call, meet at a watchmaker, or accept an escrow or authentication service.

If you already bought one

Stop wearing it, photograph everything including the serial and caseback, and have a watchmaker open the case for a movement inspection — that is the only definitive verdict. If the watch is confirmed as a fake iw371789, report the listing to the platform, keep the payment trail, and dispute through your card issuer or escrow service quickly, since deadlines are short.