A replica IW329108 is a copy of the IWC Aquatimer Automatic 42 mm dive watch. Judging one comes down to four checks: case dimensions against the genuine reference, the movement of the inner dive scale when you turn the bezel, dial and date printing under magnification, and the movement's beat rate. Copies fail at the bezel and the date window far more often than at the logo.

Check the reference before you judge the watch

The number on the caseback has to match the watch in front of you. A seller mixing an Aquatimer case with a chronograph dial, or listing a 44 mm case as this reference, is not selling a copy of the watch you asked about.

  1. Read the caseback engraving at an angle in raking light; the reference digits should be cut into the steel, not laser-printed on the surface.
  2. Measure the case width across 9 and 3 with the crown excluded, and compare it to the 42 mm figure published for this reference.
  3. Weigh the head and bracelet on a kitchen scale; thin casebacks and hollow links pull a 42 mm steel diver well under the expected range.

Test the bezel and dive scale

  1. Turn the outer bezel through a full revolution and watch the printed scale under the crystal; on a working SafeDive system the inner scale moves with the outer ring.
  2. Grip the bezel and try to lift it; any vertical play or rotational slop points to a stamped ratchet, not a machined one.
  3. Check the bezel alignment at 12; the triangle should sit centered on the marker with no drift after a full turn.

Inspect the dial, date, and lume

  1. Loupe the dial text at 10x; lettering should be crisp with even spacing and no ink bleed into the lacquer.
  2. Look at the date aperture edges; they should be beveled, with the disc flat and the numeral centered in the frame.
  3. Press each applied index with a soft probe; any rock or glue halo means it will lift with wear.
  4. Charge the lume with a phone light for 20 seconds; it should glow evenly and fade smoothly, not in patches.

Check the movement

  1. Put the watch on a timegrapher and record the beat rate; IWC automatics in this family run at 28,800 vph, and a 21,600 vph reading means a different movement inside.
  2. Wind 30 turns and listen for rotor wobble or grinding when you tilt the case.
  3. Unscrew and reseat the crown five times; cross-threading on the tube is the most common failure on copies.

Treat water resistance as unproven

No copy ships with a valid pressure test. Ask a watchmaker to test it at 3 bar before it goes near a sink, and never dive with it. ISO 6425 exists precisely because dive ratings require controlled testing that counterfeits do not receive.

Seller red flags

  • Catalog photos instead of pictures of the actual watch.
  • No movement photo and no caseback photo.
  • No return window, or a return window that excludes opened casebacks.
  • Claims of Swiss origin or 1:1 perfection with no serial details.
  • A price far under the going rate for the same copy elsewhere.

Set expectations before you buy. A replica can look close on the wrist, but it will not hold resale value, may not survive service, and should not be treated as dive equipment.