Short answer
A fake IW328013 usually fails in four places: dial printing, lume application, case and lug geometry, and the movement under the caseback. Run the checks below in order, from the cheapest and fastest to the most invasive. If a seller resists any of them, or the price sits well under the going rate for a used example with box and papers, treat the watch as a replica until a watchmaker says otherwise.
What you need
- A 10x loupe or a phone macro lens
- Diffused daylight or a neutral LED panel, no colored bulbs
- A digital caliper that reads to 0.01 mm
- A kitchen scale that reads to 0.1 g
- Reference photos of the genuine IW328013 from the official catalog and from a dealer listing
Step-by-step authentication check
- Weigh and measure the watch head, then compare the result with the factory figure you pulled from the official specification page.
- Place the loupe over the dial text and read the wordmark letter by letter, looking for thick strokes, uneven spacing, or a fuzzy edge that the genuine print does not show.
- Compare the printed reference and dial markings against your reference photo at the same angle and under the same light.
- Study the applied indices and hands for lume overflow, domed fill, or a metal frame that sits higher on one side.
- Charge the lume with a UV light for 20 seconds, then watch it fade; genuine Super-LumiNova glows a consistent blue-green and dims at an even rate.
- Inspect the date aperture for a chamfered edge, then check the date font and its alignment inside the window.
- Look at the seconds hand tip and confirm it reaches the minute track without overhang or a short fall.
- Tilt the crystal under daylight; a heavy blue or purple sheen on the outside face points to an aftermarket crystal.
- Run a fingernail along the lug edges and along the transition between brushed and polished surfaces to feel for soft, rolled edges.
- Turn the crown through its full thread travel; count the turns and confirm the signed logo is crisp and centered.
- Read the caseback engraving under magnification and compare letter depth, spacing, and the grain pattern around it with your reference photo.
- Have a watchmaker open the caseback, then compare the rotor engraving, caliber number, and movement finish with the specification IWC publishes for this reference.
- Match the serial on the caseback to the serial on the warranty card, the dealer stamp, and the box label.
Red flags in the paperwork
- A warranty card with a serial that does not match the caseback
- Blurry or low-contrast printing on the card or the booklet
- Box lining with a loose fit, glue smell, or a wrong logo weight
- A seller who will not allow an inspection at a watchmaker before payment
Getting a second opinion
Finishing on modern replica cases has improved enough that photos alone are unreliable. A watchmaker with a timing machine can confirm rate and amplitude, and can verify that the movement inside matches what the reference should carry. Budget for that inspection before you commit, and walk away if the seller will not permit it.