This guide covers identification and authenticity checks for the IWC Aquatimer Chronograph reference IW323720. It does not direct you to sellers of counterfeit watches.
Short answer
A replica IW323720 usually fails on measurements and print quality rather than on overall looks. If the case diameter, thickness, weight, dial lettering, date alignment or caseback engraving do not match IWC's own reference data, the watch is a copy no matter how good the listing photos are. Check physical measurements first, then the dial, then the movement.
What the reference should be
The IW323720 sits in the IWC Aquatimer Chronograph line, a series that IWC revised several times. Case size, bezel type, bracelet style and water resistance rating changed between generations, so figures from one Aquatimer chronograph do not automatically apply to another. Pull the exact numbers for IW323720 from IWC's own reference record, not from a marketplace listing, a forum thread or a seller's description.
Prerequisites
- Digital calipers that read in millimeters
- Precision scale accurate to 0.1 g
- 10x loupe or a macro lens
- Bright, raking light source
- IWC's published reference data for IW323720 on hand
- A watchmaker contact who can open the case
How to check an IW323720
- Write down the full reference number, case number and any engraving text from the caseback before you handle the watch further.
- Measure case diameter, thickness and lug width with calipers, then compare each figure to IWC's published numbers for IW323720.
- Weigh the watch head on the scale and note the result; copies commonly run light because of thinner case walls and bracelet links.
- Examine the dial under the loupe and check letter spacing, the position of the brand name and the crispness of every marker edge.
- Look at the date window and any magnifier; check that the disc sits level and that the numerals are centered in the aperture.
- Compare the hands for length, finish and lume fill, and check that all three hands point at the correct markers.
- Work the crown through its positions; winding should feel smooth, each position should click clearly, and the crown should screw down to a defined stop.
- Press each chronograph pusher and run the chronograph for a full minute, then reset and confirm the hands snap back to zero.
- Inspect the caseback engraving depth and font, and confirm that the reference, case number and water resistance text are consistent with each other.
- Have a watchmaker open the case and check movement finish, rotor engraving and jewel count against the caliber IWC used for this reference.
- Time the watch over 24 hours in a few positions and record the daily rate before you decide anything.
Common failure points on copies
- Case diameter or thickness off by a fraction of a millimeter, which is easy to catch with calipers.
- Dial text that is slightly too bold, too thin or spaced unevenly.
- Date window that sits a hair off center or shows a mismatched disc font.
- Caseback engraving that looks laser-etched instead of stamped deep into the metal.
- Pusher action that feels gritty, or a chronograph that resets past zero.
If you are still not sure
Take the watch to an IWC boutique or to a watchmaker with access to IWC parts and service records. They can confirm the case number, pressure-test the case and time the movement on a proper machine. Ask for the findings in writing if money is on the line, and walk away from any seller who refuses an inspection or cannot produce the papers that match the case.