A fake IW371646 is a counterfeit copy of the IWC Portugieser Chronograph reference IW371646, a watch that sits in the 41 mm Portugieser Chronograph 3716 family. The giveaway details are consistent: subdial placement at 12 and 6, the font and applied finish of the Arabic numerals, the leaf hands, the engraving on the sapphire caseback, and the finish of the chronograph movement visible through it. Judge any suspect watch against the official reference specification first, then against those physical details.
What the IW371646 reference actually is
IWC uses the 3716 prefix for its current Portugieser Chronograph line, a family of 41 mm steel and gold chronographs with a clean, symmetrical dial. The individual digits after the prefix identify the dial colour, case metal, and bracelet or strap combination. Before you compare anything, confirm the exact variant on the manufacturer's own reference page, because dial layout, date presence, and caseback style change between versions.
That step matters more than most buyers expect. Many fakes are built from photographs of a different 3716 variant, so a watch can look convincing while carrying the wrong combination of dial, hands, and reference number.
Why replicas of this reference are common
- The design is simple, so a counterfeit dial prints cleanly at low cost.
- It is a chronograph, which lets sellers advertise a "complex movement" as proof of quality.
- The case shape has no unusual curves or lugs that are hard to reproduce.
- Demand is steady, so replica factories keep the model in production.
Simple geometry cuts both ways. It is easier to copy a clean three-hand-style dial than an intricate one, but it also means small errors in proportion are easy to see once you know where to look.
Dial and hands: the fastest checks
The dial is where most fakes fail under a loupe or a phone camera zoom.
- Subdial spacing. The two registers should sit on a tight vertical axis at 12 and 6, positioned close to the centre. Wide spacing or a slight offset is a common replica flaw.
- Numerals. The applied Arabic numerals should be sharp, evenly polished, and identical in height. Soft edges, uneven lume fill, or numerals that sit proud of the dial in the wrong way point to a copy.
- Printing. Text should be crisp and level. Look for bleeding edges, uneven weight between letters, or a logo that looks painted rather than applied.
- Hands. Leaf hands should be flat, faceted, and finished on both sides. Replica hands often show tool marks or a slightly thicker profile.
- Date window. Some 3716 references have no date at all. A date aperture on a reference that should not have one is an immediate red flag.
Case, crystal, and finish
Genuine Portugieser cases are finished with a clear distinction between brushed surfaces and polished bevels. On a fake, that contrast usually softens: brushing looks shallow, edges feel slightly rounded, and the lugs lose their crisp transition. Run a fingernail along the lug edges, and check that the caseback sits flush with even gaps all round.
The sapphire crystal should be clear with a clean anti-reflective coating. Purple or green reflections, a visible halo at the edges, or a crystal that sits too high above the bezel are worth questioning.
Caseback and movement
A watch with an exhibition caseback is easier to authenticate than one without, because the movement is on show.
- Engraving should be deep, even, and correctly spelled, including the reference and serial numbers.
- Movement finishing should show consistent Geneva stripes, blued or polished screws, and clean perlage where it belongs.
- The rotor engraving should be sharp, not stamped with a soft edge.
- Chronograph pushers should start, stop, and reset with a firm, defined click. Mushy pushers are a warning sign.
If you cannot identify the calibre by sight, photograph the movement through the caseback and send the image to an independent watchmaker for an opinion. That costs far less than a bad purchase.
Paperwork, price, and seller behaviour
Documents are easy to print, so treat them as supporting evidence rather than proof. Compare the serial on the caseback, the card, and the movement where possible. A price far below the going rate for the reference is the single most reliable warning, and pressure to buy fast, refusal to provide macro photographs, or a seller who will not meet a watchmaker are all reasons to walk away.
A practical authentication routine
- Confirm the reference and its exact dial layout from the manufacturer.
- Request sharp macro photos of the dial, caseback, and movement.
- Check subdial spacing, numeral finish, and printing under magnification.
- Compare the caseback engraving font and depth with known examples.
- Have a watchmaker inspect the movement and timegrapher readings in person.
Terminology is worth a note. Sellers of replica watches describe their products as replicas or homages, while "fake" is the word buyers use when a watch is passed off as genuine. A replica sold honestly is one thing; a counterfeit sold as an original IWC is fraud, and the checks above are what separate the two.