Quick answer

A fake IW323771 usually gives itself away in four places: the caseback engraving, the movement stamp and finishing, the dial print under magnification, and the measured case size and weight. Run those four checks first. If the watch passes them but the serial cannot be confirmed by an IWC authorized service center, treat it as counterfeit until the center says otherwise.

What you need

  • A 10x jeweler's loupe or a phone macro lens
  • Digital calipers
  • A scale that reads to 0.1 g
  • Bright angled light and a lint-free cloth
  • Nitrile gloves, so you do not add oils or prints
  • Contact details for an IWC authorized service center

Step-by-step check

  1. Write down the reference number and the serial from the caseback as engraved, including the spacing between characters.
  2. Measure case diameter, lug-to-lug length, and total thickness with the calipers, then record each number.
  3. Weigh the watch head alone, with the bracelet or strap removed, and record the figure in grams.
  4. Compare your three measurements against the published IWC specification for reference IW323771.
  5. Set the loupe on the caseback text and check the depth, edge sharpness, and font weight of every character.
  6. Look at the serial on the caseback and confirm it is a single, continuous engraving rather than laser dots or a stamped overlay.
  7. If the watch has a display back, study the movement finishing through the sapphire with the loupe.
  8. Read the caliber number and Swiss or IWC markings stamped on the movement and bridge.
  9. Match that caliber number against the movement IWC lists for this reference.
  10. Inspect the rotor engraving and the rotor bearing for polish, spacing, and correct lettering.
  11. Examine the dial print at 10x, checking letter spacing, ink thickness, and alignment of the brand name with the markers.
  12. Check the hands for even finish, correct length, and clean edges where the hand meets the pinion.
  13. Operate the crown through several positions and note the winding feel, date change, and hand-setting resistance.
  14. Close the clasp and inspect the stamped logo, the spring bar fit, and the gap between links.
  15. Send clear photos of the caseback, dial, and movement to an IWC authorized service center and request a serial check.

Replica tells that appear most often

  • Caseback text that is shallow, rounded, or spaced wrong for the reference
  • A caliber stamp that does not match the movement family IWC used for this reference
  • Dial print that is too thick, too glossy, or misaligned with the applied markers
  • Case thickness a few tenths of a millimeter off, or total weight below the genuine figure
  • Machine-brushed finishes on the case flanks that run in the wrong direction
  • Serial numbers that repeat across multiple listings on the same marketplace

Before you pay

Ask the seller for the serial, the movement photo, and a written return window. Buy only from a source that accepts a third-party authentication check, and pay with a method that allows a chargeback. Counterfeit watches are illegal to import into the United States and are subject to seizure, so an unresolved serial is not a small detail. If the seller refuses a serial check or a service center visit, walk away.