The short answer

A fake IW329083 is a counterfeit of an IWC Aquatimer Automatic 42, and it is one of the easier fakes to catch once you know where to look. Three checks do most of the work. Does the outer bezel actually drive the inner dive scale? Is there a decorated automatic movement behind the sapphire caseback? Do the reference and serial numbers on the caseback, the movement and the paperwork agree? If any of those fail, walk away. The reference itself is a niche one, and that matters, because most counterfeits carrying an IW329083 number were not built to copy that watch. They were built as generic Aquatimer replicas and stamped with whatever digits the seller thought would move.

What the real IW329083 is

The IW329083 sits in IWC's Aquatimer Automatic 42 family, a 42mm stainless steel dive watch roughly 14.3mm thick and rated to 300 metres. It runs calibre 30120, an automatic based on the ETA 2892-A2, with about 42 hours of power reserve and a 4 Hz beat. The crystal is sapphire with anti-reflective coating on both faces, the crown screws down, and the dial carries a date at 3 o'clock.

The last digits of the reference matter more than people assume. On IWC references, the trailing numbers usually point to a dial, strap or bracelet combination rather than a different case or movement, so an IW329083 and its siblings are the same watch dressed differently. Confirm the exact combination against IWC's own catalogue before arguing about a specific number, because sellers on both sides of the fence get this wrong.

Where counterfeits give themselves away

The bezel

The Aquatimer uses IWC's SafeDive system. Turning the outer bezel drives an internal rotating dive scale through a small gear train. Counterfeits almost never replicate this. On most fakes the outer ring spins freely with a click and the inner scale either does not move at all or is simply printed on the dial. Turn the bezel and watch the inner scale. If it does not track the outer ring, that is your answer.

The movement

Look through the caseback. A real calibre 30120 shows finishing: a signed rotor, stripes, perlage. Fakes usually carry a low grade Chinese automatic or a Miyota, often undecorated, with a rotor engraving that is blurry or misspelled. Set the watch and watch the date change. Cheap movements flip late or sluggishly. Listen, too. A 4 Hz movement ticks eight times a second, noticeably faster than the 3 Hz movements common in budget replicas.

Case, dial and crystal

Engraving on a genuine caseback is crisp and shallow with clean edges. Fakes are often laser etched deeper and softer. Date font and window placement are common tells, as is lume that glows green when it should be blue-white and fades within minutes. Anti-reflective coating on real sapphire gives a faint blue sheen; fakes often have none, or a cheap coating that rubs off.

Numbers and paperwork

A genuine watch has a serial between the lugs and a reference on the caseback, and both appear on the warranty card and in IWC service records. Counterfeits reuse the same serial across an entire production run, which is why a quick search can turn up five supposedly different watches with identical digits. If the seller cannot say where the watch was bought and serviced, that is information as well.

What a counterfeit actually costs you

Not just the purchase price. Trademark counterfeits are illegal to import and sell, and shipments get seized and destroyed by customs. There is no service, no parts support and no resale value. Water resistance claims on replicas are marketing copy. A fake advertised at 300 metres often leaks in a swimming pool, and the gaskets are the first thing to go. A watchmaker who services IWC will usually decline to touch it, which leaves you with a paperweight that lies about what it is.

If you want the look for less

Buy pre-owned. The Aquatimer is not a hype reference, so secondary prices sit well under what a Submariner or a Royal Oak commands, and a full set with box and papers gives you something a fake never will: a serviceable movement and a resale floor. If the budget still does not stretch, a Seiko, Certina, Oris or Longines diver gives you a real dive watch with a real warranty for less than a convincing fake costs, and nobody has to lie about it.