Short answer

The IW371407 is a reference in the IWC Portugieser Chronograph line, part of the IW3714 family. Original specs: stainless steel case, 40.9 mm across, 12.3 mm thick, sapphire crystal with coating on both faces, sapphire case back, IWC calibre 79350 on a Valjoux 7750 base, 31 jewels, 28,800 vibrations per hour, 44 hours of power reserve, 3 bar water resistance. The dial is bi-compax. Small seconds sit at 6 o'clock. A combined 30-minute and 12-hour counter sits at 12 o'clock. There is no date window.

Replicas of this reference sell in three grades. The top grade copies the case profile, dial print, and hand shape. None of them use the original calibre. Most run a Chinese copy of the Valjoux 7750, and the case ends up thicker than the original. Street prices for the top grade land near USD 400 to 600.

What a replica copies

  • Case: 40.9 mm diameter, 20 mm lug width, polished bezel, brushed flanks.
  • Dial: two subdials at 12 and 6, applied numerals, leaf hands, printed minute track.
  • Crystal: domed sapphire, single or double anti-reflective coating.
  • Case back: sapphire window, reference number engraving, rotor with IWC text.
  • Strap: leather with an alligator grain, steel pin buckle.

Where replicas differ

Case thickness

The calibre 79350 shares the Valjoux 7750 base, which measures 7.9 mm thick. IWC lists the full watch at 12.3 mm. A 7750 copy plus a dial and case back adds up. Most replicas measure 13.5 mm to 14.5 mm on calipers. Ask for a photo of the caliper jaws on the case.

Subdial drive

The 7750 base puts running seconds at 9 o'clock. The Portugieser puts them at 6. Replica makers add a transfer gear to move the hand. The gear adds friction. Reports of a stalling or jumping seconds hand come up in this build. Some cheap replicas skip the gear and leave the seconds at 9 o'clock. That is the fastest tell.

Print and finish

Logo weight, numeral thickness, and the sharpness of the minute track vary by batch. Case back engraving is shallow on low grades. Check the crown and pusher shape against photos of the original.

Strap

Real alligator has a tight pore pattern and a matte finish. Embossed calf looks uniform and glossy. Alligator straps also fall under CITES rules for cross-border shipping.

Movement options in the replica market

  1. Chinese 7750 copy with a transfer gear for small seconds at 6. Common in the top grade.
  2. Chinese 7750 copy with seconds left at 9. Wrong layout.
  3. Quartz or hand-wind movement with a fake rotor. Lowest grade.

None of these has 31 jewels or a 44-hour reserve that matches the original. Service parts do not cross over to ETA or Sellita.

Checks before you pay

  1. Measured thickness under 14 mm, with a photo of calipers.
  2. Subdial hands at 12 and 6 pointing to zero after a chrono reset.
  3. Chrono minute counter advancing one step per minute.
  4. Correct reference number on the case back.
  5. Strap material named in writing, calf or alligator.
  6. No water resistance claim. Keep the watch dry.

Legal status in the US

Import of counterfeit goods is illegal in the United States. Customs and Border Protection can seize and destroy a shipment. Trademark holders can also pursue sellers. Factory names in this market change, and no public record ties a specific workshop to this reference.