The short answer
A fake IW545150 usually fails on details, not on silhouette. The dial text is a touch too heavy or too wide, the crown feels gritty when you wind it, the caseback engraving looks shallow under raking light, and the movement is decorated to imitate a finish it does not have. If you only get one look at the watch, spend it on the dial at an angle. That is where copies lose the argument.
Start with the reference, not the watch
IWC numbers run as a family plus a variant. The first part identifies the model line and case, and the trailing digits identify metal, dial, and strap. So IW545150 is a specification, not just a label. Before you compare anything, write down the expected case size, case material, dial color, strap, and movement family for that exact variant. Copy sellers count on buyers who recognize the model but not the variant.
Then read the caseback. The reference and the serial should both be there, stamped cleanly, and the serial should match the warranty card or service papers. On fakes, the engraving is often the same depth as everything else on the back, and the font runs a hair too wide or too thin.
The dial is the tell
Applied numerals and markers on a real one are cut and polished, so one edge catches light while the other goes dark. Stamped copies look flat, with edges that are slightly rounded. Run a finger over a numeral if the seller allows it, then look at it from the side.
Printing is the other giveaway. Check the crispness of the name text, the spacing between letters, and whether the subdial ring sits concentric with the subdial hand. An off-center subdial ring is common on copies and easy to miss at arm's length.
Hands should be polished on the bevel and matte on the flat, with a clean sweep and no tool marks. Blued hands shift color as you rotate the watch. Painted blue hands stay the same shade from every angle.
Case, crown, and winding feel
A hand-wound movement should wind smoothly and stop cleanly at the end of its travel. Copies often feel sandy, or keep turning past the point where the mainspring should be fully wound. The crown should pull out into distinct positions and screw down without cross-threading. Check the gap between crown and case tube. A wide gap usually means a replacement part or a poorly machined case.
Look at the lugs and the case flanks under a bright light. Real cases have crisp, consistent bevels. Polished surfaces should reflect a straight line, not a wavy one.
Movement, papers, and price
If the watch has a display back, compare the finish with photos of the real movement. Look for even perlage, screws that are polished and chamfered, and engraving that is filled rather than printed. Better still, have a watchmaker open it. That costs little and settles the question.
Papers matter, but they are also easy to fake. Check that the serial on the card matches the caseback, and that the card stock and printing look right for the period. Above all, look at the price. A genuine IW545150 does not sell far below the market range for its variant, and a price that looks too good is the oldest signal there is.
Quick checklist
- Reference and variant checked against published specs first
- Caseback reference and serial match the paperwork
- Dial printing sharp, letter spacing even, subdial concentric
- Applied markers polished, not stamped flat
- Winding smooth, crown positions distinct, no gap at the tube
- Movement finish and engraving verified, ideally by a watchmaker
- Price inside the normal range for that variant