Short answer: most searches for a fake IW545103 land on one of two things, a replica of the IWC Portuguese hand-wound reference, or a bait listing that uses the reference number to collect deposits. The replica worth paying for is the one that copies the movement architecture, carries a cleanly printed dial, and comes from a seller who will show the caseback, the winding action and the strap before money changes hands. Everything else is marketing copy.
What the reference number does and does not tell you
IW545103 is an IWC reference inside the Portuguese family. That family has run for decades across several case metals, dial colours and movement types, so the number alone does not describe one specific watch. A listing that shows only the reference and stock photography gives you nothing to verify.
References in the 5451 block are hand-wound. That detail drives most of the checks below, because it decides what you should be able to see and feel through the caseback.
Criterion 1: Movement architecture
The movement is where cheap replicas fall apart. A hand-wound original has no rotor, a slimmer case and a winding feel you can judge in five seconds.
- Pros of a correct hand-wound clone: right case thickness, a winding crown that engages with some resistance, and no spinning weight visible through a display back.
- Cons: fewer makers build them, so supply is thinner and the price is higher than a generic automatic build.
- Pros of an automatic substitute: cheap, widely available, easy to service.
- Cons: a rotor where none should be is the fastest way to spot a fake, and the extra height often shows at the caseback edge.
Recommendation: if the seller cannot state the movement type, power reserve and winding direction in writing, treat the watch as unknown rather than as a replica.
Criterion 2: Dial, hands and printing
- Pros of a strong dial: sharp index edges, even lume fill, applied numerals that sit flat, and printing that reads clean under a loupe.
- Cons: many replicas use pad printing that looks thick at 10x, plus hands with soft edges and a seconds hand that stutters.
Recommendation: ask for macro photos in daylight with the camera square to the dial. Shadow-free close-ups expose more than any studio render.
Criterion 3: Case, crystal and finishing
- Pros: correct lug profile, an anti-reflective crystal that does not turn milky at an angle, and brushed and polished surfaces that meet on a crisp line.
- Cons: over-polished edges, a domed crystal with visible distortion, and caseback engraving that is shallow or misaligned.
Criterion 4: Strap, clasp and paperwork
- Pros: a strap with stitched edges and correct buckle proportions, plus a seller who is honest that no replica ships with genuine IWC papers.
- Cons: plastic-feeling leather, a stamped clasp, and listings that imply original documentation to justify a premium.
Questions to ask before you pay
- Which movement is inside, and is it hand-wound or automatic?
- What is the measured case diameter and thickness?
- Can you send photos of the actual watch, not catalogue images?
- What is the return window, and who pays return shipping?
- Is the caseback engraved or laser-etched?
Who should buy, and who should wait
A replica IW545103 suits someone who wants the Portuguese look on the wrist, understands it is not the original, and values a correct hand-wound feel over a famous badge. Skip it if you need resale value, service history or a warranty that a watchmaker will honour. In that case, save for the genuine reference and buy from a dealer who documents provenance.