The quick answer: a replica IW371479 is judged on dial layout, case thickness, and the movement behind the caseback. The Portugieser Chronograph is a clean-dial watch, so a wrong subdial function or an extra date window shows up right away. Budget builds get the general look. Only the better tiers get the proportions right.
What you are actually copying
The IW371479 sits in IWC's Portugieser Chronograph family, the 3714 line. Genuine spec runs about 40.9mm in stainless steel, roughly 12.6mm thick, sapphire front and back, feuille (leaf) hands, applied Arabic numerals, subdials at 12 and 6, and a chronograph movement built on the Valjoux 7750 architecture (IWC calibre 79350). The classic layout has no date window. It ships on an alligator strap with a pin buckle or deployant clasp.
Dial and hand combinations change across the 3714 run, and some references are boutique or limited editions. Confirm the exact reference on a spec database before you buy anything sold as IW371479, because sellers mix reference numbers up constantly.
The checks that separate a good rep from a bad one
Subdial function, not just position
At 12 you want the 30-minute chronograph counter. At 6 you want running seconds. Cheap builds put running seconds at 12, or make one subdial a printed disc that never moves. Start the chrono, let it run two minutes, and watch which hand sweeps and which subdial accumulates. If the small hand at 6 starts ticking when you press the pusher, the movement is wrong or the dial is faked.
Case thickness
The 7750 architecture is thick, so most reps land at 14mm or more against a genuine 12.6mm. On a 40.9mm case, that extra 1.5mm reads as a slab on the wrist. Ask for a caliper photo, watch flat on a table with the jaws on the caseband. If the seller dodges the measurement, assume the worst.
The date window test
The classic Portugieser Chronograph has a clean dial. If the photos show a date at 3, it is a different reference, a fantasy build, or a rep of the Chronograph Classic. Any of those is a mismatch with the number you asked for.
Movement and rotor engraving
Ask what is inside. The usual answers: an Asian 7750, a modified A7750 with decorative plates, or a clone of the IWC calibre. The A7750 is a real chronograph movement and it works, but it is loud, and rotor engraving is typically shallow and generic. Look for a photo of the movement with the caseback open, not a marketing render.
Hands, dial print, strap hardware
Leaf hands should be polished with a slight curve, not flat stamped metal. The dial text should stay crisp under a loupe. Straps are where reps cut corners hardest: thin, shiny, stiff. A decent build ships with leather that at least smells like leather, and a buckle with clean edges.
Quality tiers you will run into
- Budget, $80 to $150: printed or non-working subdials, thick case, mineral glass, soft dial print.
- Mid, $200 to $350: working A7750, correct subdial layout, sapphire crystal, off proportions and a mediocre strap.
- Top tier, $400 and up: closer case thickness, better dial texture, clone movement in some builds, sapphire with proper anti-reflective coating.
Questions to ask before you pay
- What movement is inside, and can you send a photo of it?
- What is the measured case thickness and diameter?
- Which subdial does what when the chrono runs?
- Are these photos of the actual watch you will ship?
- What happens if it arrives with a dead chrono or a crooked dial?
The part people skip
Counterfeit watches are illegal to sell and import in the US, and shipments do get seized. There is no warranty, no service path, and no resale value. If the chrono stops, you are mailing it to someone who may not exist next year. Treat the money as spent the moment it leaves your account.