The direct answer
No genuine IWC Portugieser measures 37mm. The Portugieser family runs large: the Automatic 40 sits in the IW3583 reference group, the Chronograph 41 in the IW3716 group, and the Automatic 42 in the IW5007 group. The 37mm case in IWC's current catalog belongs to the Portofino Automatic 37, a different watch with a rounder case, a simpler dial and no Portugieser-style railroad track. So when a listing says "37mm Portugieser," you are looking at one of three things: a Portofino the seller mislabeled, a generic replica with a Portugieser-flavored dial dropped into a small case, or a vintage piece where somebody measured the dial instead of the case. None of those is a 37mm Portugieser, because IWC has not built one.
Fake Portugieser 37mm: How to Spot a Replica IWC
That is the answer. What follows is how to confirm it on a specific watch in about five minutes, and what to inspect if you are looking at a replica rather than a genuine piece.
Why this question comes up so often
Three things drive it. The first is honest confusion between the Portofino and the Portugieser lines, which share a round case and Roman numerals at a glance. The second is wrist size. Buyers with smaller wrists go looking for a Portugieser they can actually wear, find a 37mm listing, and assume IWC makes one. The third is the replica market, which loves the number 37 because a smaller case is cheaper to machine and fits more wrists, so it sells better. Sellers then borrow the Portugieser name because it carries weight.
fake portugieser 37mm alternative
What a 37mm IWC actually is
- Portofino Automatic 37, reference IW4586 family. This is the watch most often mislabeled as a Portugieser.
- Older Portofino midsize and ladies models, long out of production, frequently relisted with a wrong name.
- Vintage watches where the seller quoted the dial or crystal diameter instead of the case diameter.
How to check a Portugieser claimed to be 37mm
- Measure the case yourself. Use calipers across the 2 and 8 o'clock positions and exclude the crown. Dial width is not case width, and neither is the bezel. A 37mm claim that measures 40 on the bench tells you the listing was written by someone who never handled the watch.
- Read the caseback. A genuine IWC carries a reference number (IW plus digits), a case number, and the Probus Scafusia mark. Engraving should be crisp and cut into the metal, not printed or lasered with soft edges.
- Look at the dial printing at 10x. Portugieser dials have fine applied indices, sharp Roman numerals, and a railroad minute track with even spacing. Replicas show bleeding at the numeral edges, uneven track spacing, and subdials that sit slightly off center.
- Check subdial and date placement. On the Portugieser Chronograph, the twin subdials sit at 12 and 6. On many replicas they drift outward because the case is built around a generic movement with a different plate layout.
- Weigh the case and check thickness. A genuine Portugieser Automatic 40 is roughly 12.3mm thick with a sapphire back. A 37mm claim that measures 14mm or more is a thick case hiding a cheap movement.
- Feel the crown and date change. Winding should be smooth with firm detents. If the date flips with a grind or the corrector pin pushers feel mushy, that is a low-grade movement.
Movement and caseback tells
The Portugieser Automatic 40 uses IWC's in-house caliber 82200 with Pellaton winding and about 60 hours of reserve. The Chronograph 41 uses the in-house 69355, an integrated column-wheel chronograph with roughly 46 hours. Both beat at 28,800 vibrations per hour. Replicas almost never do. They typically run a modified ETA or Seagull base at 21,600 or with a decorated rotor plate that fakes a movement it is not. If a seller will not name the caliber and the beat rate, that silence is your answer.
Fake Portugieser 37mm: Best Legal Alternatives to the Look
What "first copy" means in a listing
Jargon matters here. AAA, 1:1, super clone and first copy all describe counterfeit goods, not a licensed tier of anything. In practice the label tells you how much attention went into the case and dial, not whether the watch is genuine. Nothing at a few hundred dollars is a real IWC, and no amount of packaging changes that. A genuine Portugieser is a five-figure watch with service records, a warranty card stamped by an authorized dealer, and a movement that a watchmaker will open without flinching.
The part buyers skip
Service is the quiet problem. Authorized service centers will not work on counterfeit watches, and many independent watchmakers decline them too because parts do not exist. Water resistance is another guess. Gaskets and case threads on replicas are not built to a rated spec, so a watch sold as 50 meters should be treated as splash-only. Then there is resale, which is close to zero, and the legal side: trafficking in counterfeit goods is a federal offense under 18 U.S.C. 2320, and U.S. Customs and Border Protection seizes counterfeit watches at the border. Selling one as genuine is where people cross from a purchase into a problem.
Questions worth putting to any seller
- What is the engraved reference number on the caseback?
- What is the case diameter measured with calipers, crown excluded?
- What movement is inside, and what is its beat rate?
- Is this being sold as a replica or as a genuine IWC?
A genuine seller answers all four without hesitation. A seller who dodges the first two is telling you what the watch is.
Bottom line
If you want a 37mm IWC, look at the Portofino Automatic 37 and stop hunting for a Portugieser in that size. If you are trying to sort a genuine Portugieser from a fake, ignore the listed size, measure the case, read the caseback, and ask for the caliber. Those three checks do more work than any photo on a product page.