The short answer
IW329112 belongs to IWC's Aquatimer Automatic line: a 42mm dive watch with an internal rotating bezel, a steel case and a factory rating of 300m. Fakes sold under that reference run from about $90 to $600. None of them are the watch. What you can judge is whether the case geometry, the bezel action and the dial printing justify the money being asked, and that takes about five minutes with the piece in hand.
I check three things first: case thickness, the bezel clutch, and the date window. If those fail, nothing else on the watch matters.
Case size and thickness
The original measures 42mm across and roughly 14.5mm thick. Replicas usually run a full millimeter or more thicker because the movement spacer is cut loose and the caseback is deeper than it needs to be. Ask for a caliper photo next to a ruler before you commit. On the wrist, the lugs curve down hard, so the watch wears smaller than the number suggests. A rep with straight lugs will feel like a puck.
Look at the brushing too. Factory finishing is fine and directional, with a crisp transition to the polished chamfer. Cheap cases show swirl marks and a rounded edge where the chamfer should be sharp.
The bezel and the SafeDive system
This is where most fakes fall apart. On the real Aquatimer, the outer ring drives the inner dive bezel through a clutch. There is no crown at 2 o'clock and no separate lock. Turn the outer ring and the inner scale moves with it, clicking cleanly at each minute.
On low-tier reps, the inner ring is either glued to the crystal or moved by a tiny crown that IWC never made. Test it: the inner scale should track the outer ring one to one, with no back play and no spongy feel. Any rep that skips this detail is a costume piece.
Dial, hands and printing
Markers on the original are applied and faceted, with lume filled flush. Replicas tend to sit the markers slightly proud or use flat stamped indices. Run a fingernail across one. If it catches on the edge, the finishing is rough.
The date window is a good tell. Correctly done, the aperture has a sharp cut and the disc sits close to the dial. Bad reps leave a visible gap and a font that is too bold. Print weight matters too: the model text should be thin and even, not heavy and slightly blurry at the edges.
Lume
IWC uses Super-LumiNova. Replicas use whatever compound is cheap that month, and it usually glows green and fades in ten minutes. Charge the watch under a lamp for twenty seconds, then look at it in a dark room. A pale green glow that disappears fast tells you what you need to know about the rest of the build.
The movement
The original calibre is based on a Sellita SW300, runs at 28,800vph and gives about 42 hours. Replicas typically carry a Miyota 9015, an A2824, or a decorated Chinese clone with a fake rotor engraving. Ask which one, in writing. The Miyota is thin and reliable and suits the case well. The A2824 is a solid workhorse but thicker, which is often why those reps wear tall.
Wind it and listen. A dry, grinding rotor is a bad sign. So is a date that flips with a visible lag past midnight.
Water resistance
Treat the claimed 300m as decoration unless a shop pressure-tested the case. Gaskets on replicas are thin, and caseback threads are often cut shallow. I would not swim in one without a test, and most sellers will not offer one.
Price tiers
- Under $120: stamped case, glued bezel, weak lume, mineral glass. Skip it.
- $200 to $350: decent case shape, Miyota movement, sapphire on the better examples.
- $400 to $600: closest match on brushing, anti-reflective coating, solid end links, correct bezel action.
Questions worth asking a wholesaler
- What movement is inside, and what is the power reserve?
- Does the inner bezel move with the outer ring, or is there a separate crown?
- What is the measured thickness with calipers?
- Is the crystal sapphire, and is the coating on the inside?
- Can you send a short video of the bezel turning and the date flipping?
Anyone who dodges those five is selling you a photo, not a watch.