Short answer

A fake IW329078 is a counterfeit watch built to resemble the IWC reference, and no replica matches the original at the parts level. The useful question is not whether a fake exists, but whether a specific example holds up on four checks: case geometry, bezel action, dial print, and movement. Most examples under a few hundred dollars fail at least two of them. Judge the watch in your hand, not the photos in the listing.

Tools before you start

  • Digital calipers, for case diameter and thickness
  • 10x jeweler loupe, for dial print and engraving
  • Kitchen scale with 0.1 g resolution, for weight comparison
  • Bright diffused light and a soft cloth
  • IWC's published specs for the reference, pulled from the official site

Step 1: Measure the case

  1. Close the calipers across the case at 3 and 9 o'clock and record the diameter to 0.1 mm.
  2. Measure thickness across the caseback and crystal, then compare both numbers with IWC's published figures for the reference.
  3. Weigh the watch head on the scale and compare with a genuine example on the same strap or bracelet.
  4. Run a fingernail along the caseband edges and the lug tops; genuine finishing has a crisp, even transition between brushed and polished surfaces.

Step 2: Work the bezel

  1. Rotate the bezel through one full turn and count the detents.
  2. Push down on the bezel at four points and look for vertical play.
  3. Check that the bezel insert sits flush, with no gap at the inner edge.
  4. Confirm the bezel returns to the 12 o'clock index with a clean click, not a soft mush.

Loose bezels and shallow clicks are the most common failure on counterfeit dive watches, and they are easy to check in person.

Step 3: Read the dial under a loupe

  1. Loupe the brand text and depth rating at 10x; counterfeit print shows ragged edges and uneven stroke weight.
  2. Check applied markers for height above the dial and for polish on the bevels.
  3. Look at the date window for a sharp cut and for the numeral sitting square to the aperture.
  4. Inspect the hands for flat, unpolished sides and for lume that sits below the frame instead of flush.

Step 4: Check the movement

  1. Unscrew and re-screw the crown ten times; thread damage shows up fast on cheap cases.
  2. Set the time and note any slack or back-play in the crown stem.
  3. Put the watch on a timegrapher and record the beat rate, rate, and amplitude.
  4. Listen with the case to your ear and note rotor rattle during a slow wrist roll.

Match the beat rate and power reserve against the caliber IWC lists for the reference. A wrong beat rate is proof of a substitute movement, regardless of how the watch looks.

Step 5: Treat water resistance as unproven

  1. Assume any water resistance claim is false until the watch passes a dry pressure test.
  2. Have a watchmaker pressure test the case before the first swim, and reseal after any caseback opening.
  3. Skip the pool entirely if the test is not available.

Step 6: Vet the seller

  1. Ask for dated macro photos of the caseback, crown, and clasp, not studio renders.
  2. Ask which movement the watch uses, by name and beat rate.
  3. Confirm the return window in writing before payment.
  4. Pay with a method that allows a chargeback if the watch arrives off-spec.

Red flags

  • Listings that reuse official IWC press images
  • Prices far below the replica market for the same reference
  • No movement details, or vague answers about the caliber
  • Sellers who refuse extra photos of the caseback
  • Claims of original parts or factory surplus

What to expect at each price band

Entry examples usually carry a low-beat movement, a stamped dial, and a hollow bracelet. Mid-range examples improve the case finishing and bracelet solidity but often keep a stock movement and a soft bezel. Top-tier replicas get closer on dial print and case geometry, yet still differ in movement architecture and serviceability. Budget for a service or a movement swap on any example you plan to wear daily.