Short answer
There is no single tell that settles a fake IW545116 question. The reference belongs to IWC's hand-wound Portuguese family, and a correct verdict comes from matching the watch against IWC's published specification for that exact reference and then looking at the movement. Work the checks below in order. Stop at the first hard mismatch.
Before you start
- 10x loupe and a bright, diffuse light
- Digital calipers for case diameter and thickness
- The published IWC spec sheet for IW545116, or written confirmation of that spec from an authorized dealer
- A watchmaker willing to open the case back
- Clear photos of a known-genuine example of the same dial variant
Step-by-step checks
- Confirm the reference exists. Ask IWC or an authorized dealer whether IW545116 maps to a specific case metal, dial color, and strap combination. Replica sellers often invent a suffix. If the number does not return a real configuration, stop.
- Measure the case with calipers. Compare diameter and thickness to the published spec, not to a listing photo. A case that runs 0.5 mm or more off, or a thickness that reads too fat, points to a replica case built around a generic movement.
- Read the dial under the loupe. Check the applied numerals for sharp edges and correct height, the minute track for even spacing, and the sub-dial for correct placement relative to the center. On fakes, printing sits slightly heavy and letter spacing drifts.
- Inspect the hands. Genuine leaf or feuille hands have a clean bevel and an even finish. Replicas show rounded edges, uneven polish, and hands that sit too close to the dial or too high above it.
- Turn the watch over. On a display-back Portuguese, look at the engraving depth, the font of the reference and serial numbers, and the finish on the case back ring. Laser-etched replica markings look shallow and slightly gray.
- Check the movement. A hand-wound Portuguese should show proper bridge finishing, clean perlage or Geneva stripes, sharp anglage, and correctly engraved markings. Look for generic Chinese or ETA-based architecture, mismatched jewel count, and finishing that skips the hidden surfaces.
- Wind it. The crown should thread smoothly if it is a screw-down, engage without grit, and build resistance evenly. A grinding or loose crown is a common replica failure.
- Examine the strap and buckle. Check stitching density, leather grain, and the stamping on the buckle tang. Replica buckles often use a thinner stamp and lighter spring bars.
- Match the paperwork. The warranty card, serial number, case back, and movement number should agree, and the seller should be able to show a service history. A missing card on a modern reference is a pricing issue, not automatically a fake, but a card with the wrong font is a stop sign.
- Have a watchmaker open it and pressure test it. This is the only step that ends the argument. Budget for the service cost before you commit.
- Sanity-check the price. A hand-wound Portuguese priced far under the market for its condition and box set is a warning, not a bargain.
Red flags that end the conversation
- Seller refuses an independent inspection or an in-person opening of the case
- Reference number that does not resolve to a real IWC configuration
- Serial on the case back that does not match the movement or card
- Movement finishing visible only on the top bridges
- Stock photos used as the only proof of condition
Hand-wound Portuguese models are copied less often than the chronographs and automatics, so most suspected fakes in this reference turn out to be mismatched parts or a redial. That is why the movement check comes before any judgment based on the dial.