A fake IW371432 is judged on four things: a 40.9 mm steel case, a blue dial with the chronograph counter at 12 and running seconds at 6, a closed caseback with engraving and a limitation number, and a 28,800 vph automatic chronograph movement. The top pick in this reference is the 1:1 grade build that keeps the solid caseback, because that one detail decides whether a fake survives a second look. The reference itself is an IWC Portugieser Chronograph from the Laureus Sport for Good Foundation editions: stainless steel, blue dial, two subdials, no date window, closed back.

Why This Reference Gets Copied So Often

The Portugieser Chronograph is a plain, legible design. There is no skeletonising, no exotic alloy, no hand-engraved dial to reproduce. A factory only has to get a round case, two subdials, thin leaf hands, appliqué numerals and a back engraving right. Most builds get two of those four correct and stop there. That is why the reference is a good test case: the flaws show up in proportion and finish, not in obvious missing features.

Criterion 1: Case Size and Profile

The original sits at roughly 40.9 mm across with a slim bezel and short, curved lugs. A fake that measures 42 mm or more spreads the dial out, pushes the subdials apart and sits wrong on a 7 inch wrist.

  • Pros of a correct case: the dial reads wide and clean, the lugs hug the wrist, the strap sits flush at the case edge.
  • Cons of an oversize case: subdials drift inward, the bezel looks thick, and the watch reads as a generic chronograph rather than a Portugieser.

Criterion 2: Dial, Markers and Subdial Layout

Two subdials, nothing at 3 o'clock, no date aperture. Applied numerals catch light and cast a small shadow; printed numerals do not. Hand length matters too: the leaf hands should reach the outer minute track, not stop short of it.

  • Pros of a correct dial: crisp printing, appliqué markers, and a sunburst blue that shifts from navy to steel grey in daylight.
  • Cons of a cheap dial: flat navy paint, blurred logo, subdial hands that sit at the wrong height, and a date window that should not exist.

Criterion 3: Caseback Engraving and Numbering

This is where most fakes give up. The closed back means every buyer flips the watch over. Engraving should have depth and a machined edge, with a limitation number that is not a repeat of a common serial.

  • Pros of a proper back: sharp cut lettering, correct spacing, a number that matches the edition run.
  • Cons of a bad back: laser-etched grey lettering, shallow lines, a display crystal that the reference never had.

Criterion 4: Movement and Pusher Feel

The original runs an automatic chronograph at 28,800 vph with a smooth sweep. The chronograph should start with a firm click and reset to zero in one snap, with no bounce on the seconds hand.

  • Pros: 28,800 vph beat, clean reset, winding that feels smooth through the crown.
  • Cons: 21,600 vph stutter, spongy pushers, a reset hand that overshoots and creeps back.

The Three Grades of Fake IW371432

Budget grade

  • Pros: inexpensive, fine for photos, easy to replace.
  • Cons: wrong case size, printed markers, hollow end links, stiff pushers, no credible engraving.

Mid grade

  • Pros: correct 40.9 mm case, 28,800 vph movement, decent dial print, usable chronograph.
  • Cons: shallow back engraving, stiff strap leather, gritty crown action, thin AR coating on the crystal.

1:1 grade

  • Pros: matched case profile, correct subdial positions, deep back engraving, sharp pusher snap, sapphire with correct anti-reflective treatment.
  • Cons: higher cost, limited stock, and movement finishing that still differs from the original when viewed through a loupe.

Which Grade Fits Which Buyer

If the watch is a daily beater and nobody will handle it, the mid grade covers the reference well. If you plan to hand it to someone who knows the brand, buy the 1:1 and check the caseback first, then the dial print, then the pushers, in that order. Collectors who want the look for a display case should skip the budget tier entirely; the wrong case width is visible from across a table.

Red Flags Before You Pay

  1. A display caseback on a reference that uses a solid one.
  2. A date window anywhere on the dial.
  3. Subdials at 3 and 9 instead of 12 and 6.
  4. Case width listed above 41 mm.
  5. Photos where the back, the crown and the pushers are never shown.

Ask for a straight-on dial shot, a caseback shot and a short video of the chronograph starting and resetting. A seller who sends all three is usually selling the grade they claim.