The strongest replica IW371433 build for most buyers pairs a 40.9 mm stainless steel case with a 7750-family automatic chronograph, a sapphire crystal, and subdials placed at 12 and 6 o'clock. That pick rests on four criteria: case proportions measured against the original reference, dial printing and register spacing, movement family and serviceability, and how the watch actually sits on the wrist. The sections below work through each criterion, then compare the three build types you are likely to encounter.
The Reference in Short
The IW371433 belongs to the Portugieser Chronograph line. IWC documents that family with a 40.9 mm case, leaf-shaped hands, applied numerals, a railway minute track, and a two-register layout that places elapsed minutes at 12 and small seconds at 6. The movement is the 79350, a Valjoux 7750 base with a 44 hour power reserve, and the case carries a 3 bar rating. A replica should match those proportions first, because the dial layout follows from the case size and the movement underneath it. Get the case wrong and nothing on the dial can rescue the watch.
Criterion 1: Case, Crystal, and Finish
Measure before you judge photos. A case that runs a millimeter and a half wide of the original changes the silhouette, and the Portugieser profile is thin enough that extra thickness shows on the wrist.
- Good signs: a case within a fraction of a millimeter of 40.9 mm, brushed flanks with polished bevels, a domed sapphire crystal with a real anti-reflective coating, and lugs finished so a strap sits flush against the case.
- Warning signs: a flat mineral crystal, a crown sitting proud of the case, sharp lug edges, and polishing that shows haze under direct light.
Criterion 2: Dial and Subdial Spacing
The two-register layout is the hardest element to fake. When a factory drops a 7750 into a case without reworking the movement, the registers land close to the right positions but the spacing often drifts. Study the gap between the top register and the brand printing, and the gap between the bottom register and the rail track.
- Good signs: applied numerals with no glue bleed, a railroad track that stays even around the full dial, subdial hands cut to the same leaf profile as the main hands, and date printing sitting level in its window.
- Warning signs: font weight that shifts between the brand name and the model line, a rail track that wobbles near 3 and 9, and lume applied unevenly across the numerals.
Criterion 3: Movement
The chronograph is the reason this reference exists, so the movement matters more here than on a three-hand watch. A 7750-family automatic gives you a working sweep, a crisp pusher feel, and a part supply that any competent watchmaker can service. Cheaper clones trade that away for a lower entry point.
- Good signs: a pusher that starts, stops, and resets with a firm click, a rotor that winds with light movement, and a chronograph seconds hand that returns exactly to zero.
- Warning signs: a stutter when the chronograph engages, a seconds hand that lands short of 12 after reset, and a movement that runs fast when the chronograph is running.
Option A: 7750-Family Automatic Build
This is the configuration recommended at the top of this guide. It copies the original layout most closely because the base movement is the same family the reference uses.
Pros
- Correct subdial positions and a chronograph that behaves like the original.
- Serviceable by independent watchmakers, with widely available parts.
- Case thickness and weight land close to the reference.
Cons
- Costs more than quartz or basic automatic alternatives.
- Heavier than the original if the factory uses a stock rotor.
- Quality varies between batches, so you need photos of the actual unit.
Use it if: you plan to wear the watch often, want a working chronograph, and care about the dial reading correctly from across a table.
Option B: Quartz or Entry Automatic Chronograph
These builds keep the exterior look and cut the movement budget. Some use a quartz chronograph module, others a low-cost automatic with a decorative chronograph bridge.
Pros
- Lowest entry point of the three options.
- Quartz versions keep time well and need no winding.
- Light on the wrist, which suits casual wear.
Cons
- Subdial sweep and pusher feel do not match a mechanical chronograph.
- Register spacing is often the weakest part of the dial.
- Hard or impossible to service; replacement is the usual outcome.
Use it if: you want the look for occasional wear and do not need a mechanical movement.
Option C: Unbranded Homage
A handful of makers sell a Portugieser-style chronograph with their own name on the dial. Same proportions, no trademark, no legal exposure.
Pros
- Legal to buy, import, and resell in most markets.
- Often backed by a real warranty and a return policy.
- Frequently uses the same 7750-family base as the replica tier.
Cons
- The dial branding is not the reference branding, which is the whole point for some buyers.
- Case dimensions may differ from 40.9 mm.
- Resale value is thin.
Use it if: you want the proportions and the chronograph without customs or legal risk.
Legal and Practical Reality
Counterfeit watches are subject to seizure at the border in the United States, and trafficking in them carries civil and criminal penalties. Orders can be intercepted, and there is no recourse when that happens. If that risk matters to you, Option C is the sensible route. If you proceed anyway, buy from a seller with a documented inspection policy and pay in a way that leaves a record.
Inspection Checklist Before You Pay
- Ask for a straight-on dial photo and measure the case with calipers in a second photo.
- Confirm the crystal is sapphire, not mineral glass.
- Request a video of the chronograph starting, stopping, and resetting.
- Check the date window alignment at a few different dates.
- Verify the strap or bracelet is the one shown, since this is the most common swap.
- Confirm the return window in writing before payment.
Work through those six steps and the decision comes down to movement and finish, not to a seller's claims about how close the watch is to the original.