If you are considering a watch advertised as an IW938274, do one thing before you talk about money: verify the reference and serial number on the caseback against the manufacturer's own records. That single step resolves most of these cases. Counterfeiters copy reference numbers wholesale from photographs, so a number that matches an online listing proves nothing at all. Ask the seller for a sharp photo of the caseback engraving, a photo of the movement with the caseback off, and the original warranty card, then compare all three. Any seller who dodges one of those requests has already answered your question.

What a Reference Number Can and Cannot Prove

A reference number describes a configuration: case size, material, movement, dial, and strap. It does not identify a single watch. The serial number does that, and only the brand's own service records or archive can confirm it. When a caseback carries a reference that belongs to a different case size or a different movement, you are looking at either a misdescribed watch or a fake. Treat the reference as a filter, not a verdict.

A Five Step Verification Routine

  1. Look up the reference on the brand's official site or reference database and note the exact diameter, movement caliber, and dial options.
  2. Compare the seller's stated specs against that record. Note every mismatch instead of waving it away.
  3. Inspect the caseback engraving under magnification. Genuine engraving has crisp, uniform edges cut into the metal. Cast or laser-etched fakes look shallow, rounded, and slightly soft.
  4. Request a movement photo at high resolution and check the finishing: striped bridges, polished bevels, blued screws, and clean lettering on the rotor.
  5. Confirm the serial on the caseback matches the serial on the warranty card and any service receipt.

Where Fakes Usually Give Themselves Away

Caseback and engraving

Engraving depth and font weight are the most common tells. On a replica, the lettering often sits too far apart, the spacing is uneven, or the reference is stamped into a generic case that was never made in that size.

Dial, hands, and date

Check the index alignment at three, six, and nine. Look at the date window: it should be centered in the aperture with a clean frame, not drifting toward one edge. Lume plots should be level and evenly filled.

Movement

Open the caseback. A genuine automatic caliber runs at 28,800 vibrations per hour (4 Hz) on most current production, with a power reserve that generally falls between 42 and 120 hours depending on the caliber. A rough rotor spin, noisy winding, or a beat rate outside the specification points to a cheap substitute movement.

Parameter Bands Worth Checking

  • Case diameter: within about 0.5 mm of the documented figure for the reference. Larger gaps usually mean an aftermarket case.
  • Case thickness: within roughly 0.3 mm. Thin cases often hide a quartz or thin automatic movement.
  • Crystal: sapphire with an anti-reflective coating on both surfaces. A sapphire crystal that fogs or shows a heavy blue tint is suspect.
  • Crown: should thread smoothly and seat flush against the case with no gap.
  • Weight: a steel case of around 40 mm should feel dense and balanced. Hollow, rattling cases are a strong negative signal.
  • Lug finishing: sharp, consistent bevels on every lug, not just the ones facing the camera.

Pitfalls to Avoid

  • Buying from a listing that only shows stock photos of the reference, never the actual watch.
  • Accepting a screenshot of a warranty card instead of a photo of the physical card.
  • Trusting paperwork alone. Stamped cards are widely copied.
  • Paying a deposit before an inspection by an independent watchmaker.
  • Ignoring a mismatched box, which often signals a watch assembled from parts.

FAQ

Is every watch sold under a reference number automatically fake?

No. Genuine watches carry the same reference across many examples. The reference only tells you what the watch should be, so the verification work is in the details.

Can a jeweler authenticate it for me?

A watchmaker with brand experience can open the case and inspect the movement. Ask for that inspection in writing, and make it a condition of the sale.

What if the seller will not open the caseback?

Walk away. There is no legitimate reason to refuse a movement photo on a watch at this level.

Bottom Line

Verification beats reputation. Match the reference against official records, insist on movement and caseback photos, and confirm the serial against the card before any money changes hands. If two or three details do not line up, assume the watch is not what it claims to be and keep looking.