The fastest way to judge a watch sold as an IW93890 is to test the reference number before you look at a single photograph. IWC writes current references as IW plus six digits, for example IW3881xx. A five-digit string such as IW93890 does not fit that pattern, so either the seller dropped or swapped a digit or the listing was copied from a replica catalog. The checks below are ranked by how fast they rule a listing in or out: reference format, caseback and case numbers, movement, then paperwork and price.
Criterion 1: The reference number format
Open the current IWC catalog and search the number the seller gave you. If it returns nothing, ask in writing for the full reference, the case number, and the serial number. A seller who cannot supply all three, or who answers with a different number each time, is describing a watch they do not have. A mismatch is not always proof of a fake, because typos happen and older references were written with fewer digits, but it is a reason to stop and ask before you send money.
Pros
- Costs nothing and takes seconds.
- Works from a text listing, before photos or payment.
- Filters out listings assembled from copied replica spec sheets, which often garble the number.
Cons
- Genuine private listings can contain typing errors, so a mismatch is a question, not a verdict.
- Vintage IWC references do not always follow the current six-digit form.
Use it when: you are scanning a long list of auctions and want to cut the field down before spending time on photos.
Criterion 2: Caseback engraving and case numbers
Ask for a sharp macro photo of the caseback in daylight. On a genuine IWC the reference and case number are cut cleanly, sit level with the surrounding metal, and use one consistent typeface. Replica cases tend to show shallow etching, uneven spacing between characters, or a font that shifts between lines. The case number on the metal should also match the number the seller quoted in the message thread.
Pros
- Photographs are cheap to request and hard to fake after the fact.
- Catches cases that were engraved after production rather than struck at the factory.
- Gives you a written record to compare against the watch you receive.
Cons
- Heavy polishing can soften genuine engraving and create a false alarm.
- Requires decent lighting and a seller willing to take real pictures.
Use it when: two listings look alike on paper and you need to choose which one to keep pursuing.
Criterion 3: Movement and case construction
If the watch has a display back, ask for a photo of the movement and a short video with the seconds hand running and the chronograph started, stopped, and reset. Genuine IWC movements show consistent finishing across the bridges, crisp rotor engraving, and screws set flat in their slots. Replica movements are often generic bases with a decorative plate laid on top, and the rotor text usually looks shallower and paler than the case printing. A chronograph that will not reset to zero, or pushers that feel spongy, points to a cheap module rather than a watchmaker's caliber.
Pros
- Reveals problems that dial photos never show.
- A running video is difficult to stage with a movement that does not work.
- Seals, crown action, and pusher feel can all be assessed in one clip.
Cons
- Only applies to watches with a see-through back.
- Finishing details are hard to read from compressed phone video.
Use it when: you are paying a four-figure or higher price and want one last check before transferring funds.
Criterion 4: Papers, service history, and price
A genuine IWC usually arrives with a warranty card or booklet carrying the same reference and case number as the watch, often with a dated dealer stamp. A card that shows a different number, or a seller who keeps the card away from the buyer, is a problem. Price is the final filter: when a steel IWC chronograph is listed far below the going rate for the same model in comparable condition, the gap is usually the replica. You can also take the case and serial numbers to an IWC boutique or authorized service center and ask them to verify the watch before money changes hands.
Pros
- Paperwork is the easiest item to check against a known-good example.
- Price anomalies are simple to spot once you have compared five or six listings.
Cons
- Boxes and cards are widely counterfeited, so they support other checks rather than replacing them.
- Serial verification through a boutique can take days.
Use it when: everything else checks out and you want a final confirmation from the brand's own service network.
What to do if the listing is counterfeit
- Ask the seller in writing for the full reference, case number, and serial number, and keep the reply.
- Walk away from any listing that keeps using a five-digit reference and will not correct it.
- If you already paid, stop the payment through your card issuer or payment platform and report the listing to the marketplace.
- Remember the ownership risk: selling counterfeit watches is illegal in the United States, shipments of counterfeit goods can be seized at the border, and IWC will not service or supply parts for a watch it did not make.
Bottom line
Treat the reference number as the first gate. A five-digit IW93890 does not match the way IWC writes current references, and that alone is enough to make you ask harder questions before you pay. Confirm the case number, watch the movement run, check the paperwork, and compare the price against real sold listings. If any of those four pieces does not line up, the listing is not worth your money or your time.