The core advice first: treat the number 31 in a listing title as a seller code, not an official model name, and buy only after the seller confirms the case diameter, the movement inside, and sends dated photos of the exact watch in stock. IWC does not sell a Portugieser Automatic 31, so two listings with the same headline can hold very different watches. Your money pays for the build, not the label.
What the 31 Tag Means in Listings
Replica sellers reuse numbers for batch codes, movement revisions, or factory nicknames. On a Portugieser Automatic, the 31 tag often follows a version of the automatic movement or the production run behind it. Because the code is not standardized, ask the seller what the number refers to and compare the answer against the photos you receive. If the reply is vague, assume the listing describes a general Portugieser style rather than a specific build.
What to Look For Before You Pay
Case and proportions
Ask for the measured diameter and thickness. The genuine Portugieser Automatic sits near 40 mm and 42 mm depending on the version, with a slim profile and long lugs. A replica that measures several millimeters thicker will sit high on the wrist and look wrong under a shirt cuff. Check the lug width as well, because a mismatched strap size is hard to correct later.
Movement
Request a photo of the movement through the case back and a short video of the seconds hand sweeping. A smooth sweep near 28,800 vibrations per hour points to a modern automatic. Ask about hacking, meaning the seconds hand stops when you set the time, and about hand winding. Genuine versions use IWC's Pellaton winding with reserves of 60 hours or about seven days, so a seller who claims the same reserve on a replica is guessing.
Dial, hands, and crystal
Compare the layout against the version you want. The smaller automatic uses a small seconds subdial and no date, while the larger version adds a power reserve display and a date. Look at the printed text, the applied numerals, and the shape of the leaf hands. Blued hands should show a deep even tone, not a painted blue. The crystal should be domed sapphire, since flat mineral glass or a heavy blue tint is a downgrade.
Strap, clasp, and finish
Check stitching density, leather grain, and the clasp engraving. Polished and brushed surfaces should meet along a crisp line. Plated cases wear through at the lugs and case back, so ask what base metal and coating the seller uses.
Parameter Bands to Compare
- Case diameter: 40 mm to 43 mm across versions
- Case thickness: 12 mm to 15 mm, and thinner builds sit closer to the genuine profile
- Lug width: 20 mm or 22 mm, matching the strap you plan to use
- Movement beat rate: 28,800 vph (4 Hz) is the common target
- Power reserve: 38 to 45 hours is realistic for a replica automatic
- Crystal: domed sapphire with anti-reflective coating on both faces
- Water resistance: enough for splashes only, so do not swim with it
Common Pitfalls
- Stock photos from the brand instead of photos of the actual watch
- A Swiss made claim on a replica, which is a marketing label, since the Swiss Made definition is regulated and tied to manufacturing in Switzerland
- No movement photo, no return window, or a seller who avoids video
- Gold plating that fades at the crown and lugs within months
- A date or power reserve display in the wrong place for the version you ordered
- Pressure testing claims with no stated method
FAQ
Is the 31 an official IWC size?
No. The Portugieser Automatic family is built around roughly 40 mm and 42 mm cases, and 31 does not appear in the official naming. Treat it as a listing code and confirm the real measurements with the seller.
Which movement should I expect?
Most replicas in this style run an Asian automatic with a 28,800 vph beat rate. Ask for the movement name, a photo, and the measured power reserve. A reliable unit that keeps time matters more than the engraving on the rotor.
How do I check the watch when it arrives?
Set the time, watch the seconds hand for stutter, wind it fully, and time the reserve overnight. Inspect the lugs for plating wear and the dial for dust under the crystal. Report problems inside the return window.
Should I pay extra for a Swiss movement claim?
Only if the seller can show the movement and explain the difference. The Swiss Made label carries legal weight in Switzerland and applies to complete watches, so a replica cannot carry it in a meaningful way.