Quick answer
If you are looking at a watch sold as an IWC with the reference IW323724, start with the number itself. IWC references read IW plus six digits. Look that number up on IWC's own site. If nothing comes back, or the result is a different model entirely, the listing is already wrong and no amount of case inspection will fix it. Past that, fakes fail in three predictable places: the movement, the dial printing, and the engravings on the caseback.
What the reference number actually tells you
IWC builds references in blocks. The IW prefix is the brand, the next four digits usually point to a family, and the final two narrow it down to dial color, case metal, and bracelet or strap. So IW323724 places the watch in the 3237 group with a specific configuration. That matters because sellers of copies like to borrow a real number and hang it on the wrong watch. When the number, the dial layout, and the case metal do not agree with each other, you are looking at either a frankened watch or a straight fake.
Ask the seller to write the reference and the case number down. Then ask IWC or an authorized dealer whether that pairing exists. It takes one email.
Checks that catch most copies
- Dial printing. Genuine IWC text is crisp at 10x magnification. Letter spacing is even, the brand mark sits where it should relative to the date window, and the minute track lines are uniform. Copies show fuzzy edges, ink that pools slightly, or a logo riding a fraction too low.
- Hands and applied markers. Look at the polish. Real hands have flat, mirror facets with hard edges. Fakes often show rounded or wavy edges under a loupe.
- Case finishing. Brushed surfaces should run one direction on each plane, with polished bevels that stay narrow and sharp. Copies blur that transition, and the lug edges feel soft rather than cut.
- Caseback engraving. Genuine engraving has depth and slight variation. Fakes are shallow and laser-uniform, with a flat bottom that catches light the same way everywhere.
- Crown and winding. A genuine crown is signed, threads smoothly, and the winding action feels tight with no grit.
- Weight. Use this as a hint only. A steel copy of a steel watch can land within a few grams, because the case is the case. It is far more useful on gold references.
The movement is where replicas stop trying
Modern IWC watches run in-house calibers, and that is the hardest thing to copy at a price. Open the caseback and you are looking at finishing quality, not decoration. Real perlage is even and hand-applied. Fonts on the rotor engraving are consistent. Jewel settings sit flush. A decorated ETA or Asian clone can look busy in a photo, but under a loupe the finishing is shallow and mechanical rather than careful.
Better still, have a watchmaker compare the movement number to the case number. Service centers can confirm whether those two belong together, and that single check settles almost every argument.
Box, papers, and the paper trail
A full set proves nothing on its own. Copies ship with cards, booklets, and hang tags every day. Instead, compare the serial on the warranty card against the caseback engraving, check the date format and dealer stamp, and call the dealer named on the card. If the dealer has no record, treat the papers as props.
Before you pay
- Ask for movement photos with the caseback off, shot in daylight, not studio lighting.
- Get the reference and case number in writing, in the listing itself.
- Have a watchmaker open it during any return window.
- Compare the price against current market for that exact reference. If it is far below, that is your answer.
On "1:1" replicas
A high-end copy can survive arm's length. It will not survive a loupe on the dial, and it never survives an open caseback. If you want the look, buy the copy knowing exactly what it is. If you want the watch, pay for the real thing from someone who lets you verify it first. Those are two different purchases, and mixing them up is how people get burned.