The best fake IW371784 is the top-tier 1:1 build: the one that pairs a working column-wheel chronograph with a correctly proportioned two-register dial and a case that stays within a millimetre of the genuine Portugieser Chronograph. The tiers below were judged on five things: dial printing and lacquer depth, subdial spacing and hand shape, case profile and crystal height, chronograph feel and reset behaviour, and the finish of the caseback, strap and buckle. Price, packaging and seller photography were left out of the scoring.

What the IW371784 reference tells you before you buy

The IW3717 numbering sits inside the IWC Portugieser Chronograph family, so the watch you are comparing is a two-register chronograph: small seconds at 6 o'clock, a 30-minute counter at 12, a date aperture at 3, leaf-shaped hands and a thin bezel around a silver-white dial. Genuine examples run a little over 40 mm across and sit around 13 mm tall. Confirm the exact variant with the seller before paying, because dial colour, strap and hardware change between reference numbers in that family, and a replica sold as one variant often turns out to be built from another.

What to verify first:

  • That the seller names the reference and the dial colour, not just "Portugieser chrono".
  • That photos of the actual watch exist, including a macro of the subdials.
  • That the chronograph is shown running and resetting in a video.

Dial printing and lacquer finish

The dial separates tiers faster than anything else on this watch. A good replica dial has a soft silver-white lacquer with a slight sheen, crisp printing under the numerals, and a "SWISS MADE" line at the bottom that interrupts cleanly around the small seconds subdial rather than running straight through it.

Strengths of a 1:1 dial:

  • Applied numerals and markers with polished top surfaces and defined edges.
  • Text weight on the brand line and "Automatic" that matches the reference at arm's length.
  • Even lacquer with no blotching under raking light.

Weak points on cheap dials:

  • Flat pad-printed text that looks grey rather than black.
  • Numerals that sit proud of the dial with visible glue or gaps.
  • "SWISS MADE" printed as one continuous line under the subdial.

Best for: anyone who wears the watch with short sleeves or photographs it. If the dial is wrong, nothing else rescues the build.

Subdial spacing, hands and date window

The two registers must stack on the vertical centre line, one at 12 and one at 6, with the same diameter as the reference. Cheap builds stretch or crowd the spacing to fit an off-the-shelf movement, and the error is visible from a metre away once you know to look for it.

Strengths of a 1:1 build:

  • Leaf hands with correct curvature and a slim, tapered tip.
  • Subdial rings that are recessed into the dial with a sharp step, not printed flat.
  • A date aperture with a clean bevel and a font that is not visibly bolder than the reference.

Weak points on cheap builds:

  • Counter hands that are too thick or too short.
  • Printed subdial rings that disappear at an angle.
  • Date wheels that sit deep in the aperture or show a white edge.

Best for: buyers who plan to wear the watch daily. Recessed subdial rings catch light the way the genuine does, and that single detail carries most of the illusion.

Case profile, crystal and thickness

This is the most common giveaway and the hardest to fix. A chronograph movement with a transfer module adds height, so many replicas sit one to one and a half millimetres thicker than the genuine, with a crystal that stands proud of the bezel instead of sitting nearly flush.

Strengths of a 1:1 case:

  • Lugs with the correct downward curve so the watch hugs the wrist.
  • A box-domed sapphire that clears the bezel by a hair.
  • Polished bezel and brushed caseband with a clean transition line.

Weak points on cheap cases:

  • Visible slab sides and a flat caseback that rides up on the wrist.
  • Crystal edges that catch on a cuff.
  • Lug holes drilled off centre, which makes strap changes awkward.

Best for: anyone with a wrist under 7 inches. On a smaller wrist the extra height is the first thing people notice, so pay for the thinner case or choose a different model.

Chronograph movement and pusher feel

The current reference runs an in-house column-wheel chronograph calibre. Replicas use a reworked 7750-family base or a Chinese chronograph with a transfer module, and the difference shows up in the pushers: a column-wheel design starts and stops with a short, dry click, while a cam-actuated copy feels soft and slightly spongy.

Strengths of a good chronograph build:

  • Crisp start, stop and reset with the seconds hand snapping back to zero.
  • No stutter on the running seconds at 6.
  • Pushers that travel evenly and return under their own spring.

Weak points:

  • Reset that leaves the chrono hand a second or two off zero.
  • A rattling rotor and a winding action that feels gritty.
  • Instructions that forbid using the chrono, which defeats the point of the watch.

Best for: buyers who will actually use the chronograph. If you only want the look, a quartz or non-running-counter build costs less, but it will never feel right in the hand.

Caseback, strap and buckle

The reference has a sapphire display back, so the movement is on show and the engraving around it has to be sharp. Strap quality matters more than most buyers expect, because a stiff, glossy strap makes a good case look cheap.

Strengths:

  • Deep, laser-cut or etched caseback text with even spacing.
  • Alligator-grain leather with a matte finish and hand-stitched edges.
  • A signed buckle or deployant with the logo centred and cleanly stamped.

Weak points:

  • Shallow engraving that fades at an angle.
  • Strap leather with a plastic sheen and machine-flat stitching.
  • Buckles with an off-centre or overweight logo.

Best for: buyers who keep the watch on the original strap. If you plan to swap to a third-party strap immediately, spend the difference on the case and dial instead.

Red flags in listings

  1. Claims of "Swiss made" or "Swiss movement" on a build that clearly uses an Asian chronograph base.
  2. Tier names like AAA+, mirror quality or super clone with no macro photos to back them up.
  3. Stock images only, or photos that show two different watches across the set.
  4. No video of the chronograph running, resetting and returning to zero.
  5. A refusal to show the subdial rings, the date aperture or the caseback in close-up.

Which tier fits which buyer

If you want one watch to wear often and be judged up close, take the top tier: correct case height, recessed subdials and a crisp chronograph. If the watch is a weekend piece and nobody will handle it, the mid tier is a reasonable trade, accepting a slightly thicker case and softer pushers. If you are buying to test whether the Portugieser shape suits your wrist at all, buy the cheapest build that still has a two-register layout, then upgrade once you know the answer.