Answer first
IW329134 is an IWC Schaffhausen reference number. IWC writes references as the letters IW plus six digits. I could not confirm a current public spec sheet for IW329134, so treat any listing that cites this number as unverified until the maker's own product page matches it. Counterfeit cases carry real reference numbers copied from catalog photos. A correct number stamped on a caseback proves nothing about the watch.
What the reference tells you
- Prefix. The letters IW come before the digits on IWC paperwork and casebacks.
- Family block. The leading digits group a model family. Watches in one family share a case shape, movement base and water resistance class.
- Variant digits. The final digits mark dial color, strap or bracelet, and market.
- Serial. A separate serial number sits next to the reference. Buyers can ask IWC to confirm that the pair matches a produced watch.
Where fakes fail
- Engraving depth. Laser marking on counterfeit casebacks looks shallow and flat. Genuine engraving has cut edges and a matte base.
- Font. IWC uses a set typeface. Look at the numeral 1, the letter G and the spacing between digits.
- Dial print. Fake dials show thick paint, uneven kerning and a raised logo.
- Movement. Counterfeit sport watches use third party automatic calibers. Rotor text, jewel count and finish do not match the maker's spec.
- Weight. A steel case with a hollow bracelet feels light. Genuine bracelets use solid links.
- Lume. Aftermarket lume glows green or blue with a short charge time.
Checks to run before payment
- Photograph the caseback under raking light. Compare the engraving to a maker photo of the same reference.
- Ask for the serial number and the reference number. Run both through the maker's service portal or an authorized dealer.
- Request a movement photo with the caseback off. Refuse sellers who will not open the watch.
- Compare the watch to the maker's spec sheet: case diameter, lug width, thickness, water resistance rating.
- Check the paperwork. Boxes, booklets and cards get copied. A card with a mismatched serial number is a fail.
- Meet at an authorized dealer or a watchmaker. A pressure test and a rate check take minutes.
What photos cannot settle
Photos cannot show movement finish, gasket condition or bracelet end link fit. Replicas built from cloned movements pass a visual check. A hands on inspection by a watchmaker with a caseback tool is the reliable test. Budget for that step on any private sale.