Short answer
IW329096 sits in the IWC Aquatimer Automatic 42 family. IWC lists that line with the IWC calibre 32111, a 42 mm case, 300 m water resistance, and a SafeDive inner rotating bezel. The full spec sheet for IW329096 alone is not published in a searchable form on iwc.com, so confirm case metal, dial color, and strap with an authorized dealer. Replica sellers reuse the number as a label. In most listings the label does not match a real watch.
Caseback and serial number
A real IWC caseback carries the reference number, a serial number, and the words International Watch Co. The engraving is laser cut. Edges are crisp and shallow. A fake shows deep, rounded engraving, a wrong font, or the same serial number across several auctions. IWC runs no public serial lookup. An authorized service center can match the number to the movement and the service record.
Movement
The Aquatimer Automatic 42 runs the IWC calibre 32111 with a 120-hour power reserve. A display back shows the rotor, Geneva stripes, and perlage on the bridges. Replicas in this family use a low-grade automatic, a printed cover plate, or a solid caseback that hides the movement. Check the rotor text and the balance rate: 28,800 vph, 4 Hz.
Bezel, crown, and lume
The inner bezel turns with the crown at 4 o'clock. Real bezels click in 60 steps with no backlash. Fakes feel loose or turn with the outer ring. Factory lume on hands and markers glows green-blue and fades over hours. Replica lume glows weak and dies in minutes. Crown threads on a real IWC engage in about two turns and seal against a gasket.
Case, crystal, and weight
A 42 mm steel Aquatimer weighs roughly 120 g to 150 g on a rubber strap, more on a bracelet. Replicas run light because the case is plated brass or thin steel. Sapphire crystal on a real watch shows almost no distortion and takes a fingerprint in a soft pattern. Mineral glass on a fake has a blue edge under a lamp.
Box, papers, and price
IWC ships a box, a warranty card, and a manual. Card numbers should match the caseback. Since 2022 IWC extends the warranty to eight years when the owner registers the watch. A real Aquatimer Automatic 42 sells above 4,000 USD on the secondhand market. Listings under 1,500 USD for a steel IWC diver are fakes or frankens. Ask for a close photo of the caseback, the movement, and the card. Send the numbers to IWC and let them confirm.