A fake IW371704 is any watch offered as an IWC Portugieser Chronograph ref. IW371704 that was not built by IWC Schaffhausen. The real reference sits in the IW3714 family, a stainless steel Portugieser Chronograph that ranks among the most copied IWC models. Counterfeits run from cheap quartz imitations to convincing case copies built around third-party movements. The movement and its finishing decide the question, because that is the part replica factories cannot reproduce at a profitable cost.

Fake, replica, and franken: what each term means

  • Fake or counterfeit: a complete copy presented as an IWC watch.
  • Replica: the same object, sold with the brand name and design copied from the original.
  • Franken watch: a genuine case or dial combined with non-genuine parts, often a swapped movement or aftermarket hands. These fool buyers because part of the watch is real.

Genuine reference points to memorize

The IW371704 is a Portugieser Chronograph with a round steel case measuring roughly 40.9 to 41 mm, a slim bezel, feuille hands, applied Arabic numerals, and a two-register layout that puts the 30-minute counter at 12 o'clock and small seconds at 6. Inside sits IWC caliber 79350, a Valjoux 7750 base reworked and finished by IWC. It beats at 28,800 vibrations per hour with a power reserve near 44 hours, and the case back is a display back, so the movement can be examined without tools. Dial colors and case metals vary across the IW3714 family, so confirm the exact variant against official IWC reference data before you compare.

Before you inspect

  • A 10x jeweler's loupe or a macro lens
  • A bright desk lamp you can angle across the dial
  • Official reference photos of IW371704 for side-by-side comparison
  • A soft cloth, plus a watchmaker if the case must be opened

Step-by-step inspection

  1. Turn the watch over and study the movement through the display back. A genuine caliber 79350 shows Geneva stripes on the bridges, circular graining on the base plate, blued screws, and an engraved rotor. A blank or coarse movement means the watch is not IWC.
  2. Check the rotor engraving with the loupe. Letters must be sharp, spaced with care, and cut into the metal. Text that sits flat on the surface, without depth, points to a counterfeit.
  3. Inspect the dial print at 10x. The IWC signature and the Schaffhausen text should be crisp with no ink bleed, and the subdial rings should be concentric. Blurry text and uneven rings are the most common replica faults.
  4. Study the applied numerals and hands. Genuine markers sit flush with even lume fill. Replica markers often sit crooked, sit too high, or carry lume that spills past the edge.
  5. Run the chronograph. Press start, stop, and reset in sequence. Genuine pushers have short, firm travel, and reset snaps the hand back to zero in one motion. A spongy pusher or a hand that drifts past 12 is a warning.
  6. Measure the case with calipers if you have them. Confirm the diameter and lug width, and check that the crown sits centered between the two pushers.
  7. Read the case back engravings with the loupe. The reference number, serial number, and Swiss Made text must have sharp edges and match the font used on the model. Shallow engraving with rounded edges indicates a cast copy.
  8. Weigh the watch in your hand. A steel Portugieser Chronograph feels dense for its size. Counterfeit cases often feel light and cold because of lower-grade alloys.
  9. Compare the strap and buckle. Genuine alligator has irregular scale patterns and a signed pin buckle. Replica straps are often embossed calf leather with a stamped buckle.
  10. Check the box, the warranty card, and the serial number. Genuine papers carry a serial that matches the case back, and the card stock and print quality are high.

Red flags in listings

Authentic IW371704 watches trade in the thousands of dollars on the secondary market, and full sets sit higher. A listing at a few hundred dollars, a seller who will not send close-up movement photos, stock catalog images instead of real photos, and claims of Swiss made with no service history are the classic signals of a replica. Sellers who avoid the question of the movement or refuse a video call deserve the same suspicion.

If you already own a suspect watch

Take it to an authorized IWC service center or an independent watchmaker who services Valjoux 7750 movements. A movement inspection takes minutes and settles the question. Keep the seller listing, the photos, and the messages. If the watch was sold as genuine, those records support a claim with the selling platform or your card issuer.