Quick answer
The IW329100 is an IWC Aquatimer Automatic 42, a steel diver with a 42 mm case, 300 m of rated water resistance and IWC's SafeDive bezel, where the outer ring drives a rotating scale inside the crystal. A replica of it runs from about $70 to $450 depending on movement and finishing. The top tier copies the case profile, dial print and rubber or steel bracelet well enough to pass at arm's length. Cheap builds fall apart on bezel action, crown threads, lume and noisy rotors. If you check nothing else, check the bezel and the crown.
Why this reference is hard to fake well
Most dive watch replicas are simple. One outer bezel, one insert, done. The Aquatimer is not that. Its bezel sits on the outside but turns a ring inside the crystal, and the two have to stay indexed to each other. That takes a gear train inside the case, and that is exactly where low-end builds cut corners.
Add the quick-change bracelet system, a case profile with brushed flanks and polished bevels, and a dial with real layered depth, and you have a watch that punishes lazy tooling.
Bezel and inner ring
On a good example the outer bezel turns in 60 firm clicks with no wobble and no dead zone. The inner ring lines up with the outer triangle at every position and returns to zero after a full turn. On weak replicas it grinds, drifts, or the inner ring sits a few degrees off. I turn a full circle at a slow pace, then snap a quarter turn and check alignment. Anything off by more than a hair is a build I would skip.
Crown, stem and caseback
The crown should unscrew in about two and a half turns with a smooth, slightly damp feel. Cheap builds have gritty threads, wobble at the stem, and crown guards that are too soft or too sharp. Look at the caseback engraving: crisp, deep lettering on a good build, shallow laser etching on a bad one.
Dial, hands and lume
Check the print weight of the brand name and the depth rating. Replica text is often bolder or lighter than the original. Applied indices should sit flat and reflect with no haze at the edges. Lume is the giveaway nobody mentions. Charge it under a lamp for a minute and watch. Genuine-grade lume glows bright and fades over hours. Replica lume starts dim and dies inside twenty minutes.
Movement tiers
Three tiers show up in this reference. Below $120 you get a low-grade automatic or a quartz with a decorative rotor. From $150 to $260 you get a Miyota 9015 or a Seagull ST automatic, both 28,800 vph, both serviceable. Above $300 you get a clone of the in-house calibre, sometimes a decorated ETA 2824. Ask what beats inside before you ask the price. A seller who cannot name the movement is not a seller worth buying from.
Price bands, in plain terms
- $70 to $120: rough case, flat dial print, bezel that feels like a bottle cap.
- $150 to $260: the sweet spot. Good case, decent bracelet, Miyota or Seagull inside.
- $300 to $450: best finishing, closest dial, clone movement, proper weight on the wrist.
Anything above that range is usually markup, not a better watch.
What to ask before paying
- Which movement, and what frequency does it run at?
- Is the bezel indexed at zero, and does the inner ring return after a full turn?
- Photos of the exact watch, not stock images.
- Case thickness, measured with calipers.
- Return policy if the bezel or crown shows up bad.
Where replicas still lose
Water resistance is the honest answer. A replica can print 300 m on the dial, but nobody pressure tested it, and the gaskets are not the same spec. Do not swim with it, no matter what the listing says. Service is the second problem: an independent watchmaker will not stock parts for a clone movement, so one failure can mean a dead watch. Resale value is zero. Customs seizures happen, so treat the money as spent the day it ships.
None of that makes the hobby pointless. People buy these to wear a shape they like without spending several thousand dollars, and a well-built replica IW329100 does that job. It is not the watch the dial claims to be. Accept that and you will choose better.