The short answer

IWC has never released a Portofino called the "140th Anniversary." The company was founded in 1868, so its 140th year fell in 2008, and no Portofino anniversary series came out of that year. The watch most sellers mean when they use the phrase is the Portofino Automatic 37 from the 2018 "150 Years" Jubilee line, ref. IW4581xx, with a white lacquered dial and blue hands. A listing that calls a watch a "Portofino 140th Anniversary" has already mismatched the name to an IWC reference, so read the rest of the listing with care.

Start with the reference number

Every IWC has a reference and a serial. Ask the seller for a clear photo of the caseback engraving. On the Jubilee Portofino Automatic 37 the reference sits between the lugs, and the serial is a separate number. Check both against the IWC reference archive before you discuss price. A seller who cannot supply the photo, or who sends a stock image, has given you the answer already.

Authentication checks, in order

  1. Measure the case. The Portofino Automatic 37 is 37 mm across and about 9.4 mm thick. Replica cases run large or thick because the builder reuses a generic case.
  2. Read the dial text. "IWC" and "SCHAFFHAUSEN" should sit tight and even, with consistent stroke weight. Replicas show crowded letters, uneven spacing, or paint that sits above the surface.
  3. Inspect the hands. The Jubilee Portofino uses slim leaf hands in blued steel. Fakes use painted steel, and the blue looks flat under a loupe.
  4. Check the date window. The aperture should be cleanly cut with a sharp bevel, and the date disc should center in the window.
  5. Match the caseback style to the reference. Note whether the reference uses a solid or exhibition back, then confirm the watch matches. Mismatches are the most common replica tell.
  6. Look at the crown. The IWC logo on the crown should be crisp and centered. Replica crowns show a soft, shallow stamp.
  7. Weigh the watch. A genuine 37 mm Portofino on a strap lands near the published weight for that reference. Light, hollow-feeling cases point to a copy.
  8. Compare the movement. Ask for a photo of the movement with the back removed, then match the calibre number to the reference.

Red flags in the listing itself

  • Price far below the current secondary market for the reference.
  • Grading language such as "AAA" or "1:1" instead of a reference number.
  • Box and papers offered as a set with no serial match.
  • Photos borrowed from a dealer site, which you can check with a reverse image search.
  • A refusal to send a caseback photo or a video of the running watch.

Legal note for US buyers

Counterfeit watches are illegal to import and to sell in the United States. US Customs can seize a counterfeit shipment, and the buyer loses the money with no recourse. Trademark counterfeiting also carries criminal exposure under federal law. If a watch turns out to be a copy, you have no warranty, no service path through IWC, and no resale value.