Short answer

IW329112 shows up in seller lists as an IWC Aquatimer Automatic reference. The number is not confirmed in official IWC material reviewed for this guide. IWC changes the last digits when the dial or the strap changes, so ask for a caseback photo before you pay. A copy of this watch is a 42 mm steel dive watch with an inner bezel. Good copies sell for $200 to $450. Copies under $150 use plated cases and low-grade movements.

What the reference covers

The 42 mm Aquatimer Automatic has a steel case, a sapphire crystal, and an inner bezel that turns with a second crown on the case side. The outer bezel is fixed. IWC introduced the Aquatimer line in 1967. The minute track sits under the glass, so the dial print and the bezel scale both matter when you compare a copy to a real watch.

Specs to check

IWC's listing for the 42 mm Aquatimer Automatic gives the numbers below. Measure a copy against them.

  • Case: 42 mm across, crown excluded. Copies often run 0.5 mm to 1 mm wide.
  • Thickness: close to 14 mm.
  • Water resistance: IWC rates the model at 300 m. A copy carries no such rating.
  • Crystal: sapphire with anti-reflective coating on both faces.
  • Movement: IWC caliber 30120, a Sellita SW300-1 base, 25 jewels, 28,800 vph, about 42 hours of reserve.
  • Date: window at 3 o'clock, quick-set.

Movements in copies

Three movements turn up in replicas of this model. An Asian clone of the ETA 2824-2, a Miyota 9015, and a clone of the Sellita SW200. All three beat at 28,800 vph, hack, and hand-wind. The 9015 runs about 42 hours on a full wind. The 2824 clone runs about 38 hours. Ask the seller which one is fitted. A 9015 winds with less noise. A 2824 clone is easier to service in the US because parts are common.

Build checks

  • Caseback engraving. Reference, serial, and the "Swiss Made" mark. Compare letter spacing to a photo of a real caseback.
  • Inner bezel. It should turn with light drag and no free play. A loose crown is a common fault.
  • Dial print. Check the weight of the IWC logo and the position of the text above 6 o'clock.
  • Markers. Applied, level, and filled to the edge. Lume that spills over an index is a reject.
  • Bracelet. End links should sit flush with the case. Look for gaps at the lugs.
  • Weight. A steel case on a steel bracelet feels dense. A plated alloy case feels light. A kitchen scale tells them apart.

What no replica gets right

Water resistance. IWC pressure-tests each watch to 300 m. A copy leaves the factory with gaskets that are not tested. Do not swim or dive with it, even after a shop reseals it. Lume is the second gap. Copies glow for 30 to 60 minutes. The real watch glows for hours. Third, the crown action on the inner bezel. Real IWC crowns feel damped. Copies click or grind.

Price bands

  • $80 to $150: plated case, mineral glass, low-grade movement, loose bracelet.
  • $200 to $400: 316L steel, sapphire, clone 2824 or Miyota 9015, decent bracelet.
  • $450 and up: better case finishing, closer dial print, top-grade movement.

Questions to ask before you pay

  1. Send a photo of the caseback with the reference and serial readable.
  2. Name the movement, the beat rate, and the power reserve.
  3. Give measured case diameter and thickness.
  4. State the crystal material.
  5. State the return window and who pays return shipping.

Bottom line

Verify the reference from the caseback. Confirm the movement. Pay with a method that allows a chargeback. A $300 copy of a 42 mm dive watch is a fair buy if you accept that the 300 m rating is a marketing line, not a test result.