The safest pick for most people is a mid-to-upper tier replica IW371648 built on a 7750-derived chronograph movement, because that combination gets the 41 mm case proportions, the sunken subdials at 6 and 12, and the pusher feel close to the original without the fragility of a thin decorated movement. The criteria that matter, in order: case geometry and brushing, dial printing and subdial depth, movement choice and serviceability, crystal and caseback execution, then strap quality. Everything below is about how to judge those five things before you pay.
What the IW371648 actually is, and what a copy has to match
The IW371648 sits inside the IWC Portugieser Chronograph family, the IW3716 line. That family shares a 41 mm stainless steel case, roughly 13 mm thick, a domed sapphire crystal, a 30 m water resistance rating, and the in-house calibre 69355 with a column wheel and vertical clutch. Reference suffixes in this family mostly track dial color, strap type, and boutique editions, so the case, crystal, and layout carry across the line. That is good news for replica buyers: a factory that nails one IW3716 reference usually nails the others, and spare parts, straps, and crystals are shared.
What that means in practice is that you are not shopping for a one-off. You are shopping for how well a factory executed a well-known layout. The tell is never the logo. The tell is the subdial depth, the printing weight, and the gap between the pushers and the case band.
Criterion 1: Case geometry and finishing
The Portugieser case is deceptively simple. Thin bezel, long lugs with a slight downward curve, and a mix of polished and brushed surfaces that only reads correctly when the transitions are sharp. Cheap copies soften every edge because the case is cast and then lightly polished. Better copies are machined and hand-finished at the lugs and case flanks.
- Pros of spending here: correct lug curve means the watch sits flat on the wrist instead of standing up; sharp case flank transitions survive close inspection; pushers line up with the crown.
- Cons: this is the single most expensive thing to get right, so a cheap case with a good dial is a common and disappointing combination.
Check the lug tips under a light. If the brushed grain runs in one direction and stops cleanly at the polished bevel, the case is worth the money. If the brushing wanders or the bevel looks rolled over, walk away.
Criterion 2: Dial, printing, and subdials
The layout is two subdials, running seconds at 6 and a 30-minute counter at 12, with applied numerals and leaf hands. Replica quality separates fast here.
- Good signs: subdial rings sit visibly below the main dial plane; printing is thin and dense rather than fat and gray; applied indices have a crisp step and lume that matches across all of them; the minute track is continuous and evenly spaced.
- Bad signs: flat subdials printed on the same surface; date window with a visible plastic ring or misaligned cut; hands that are too short or too flat to catch light; blue-ish lume on an otherwise warm dial.
A correct sunken subdial is the hardest single detail to fake, and it is the first thing an experienced eye catches at arm's length. If the subdials look pasted on, nothing else on the watch will save it.
Criterion 3: The movement decision
Replicas of this reference generally come with one of three approaches: a basic Asian 7750, a decorated 7750 with a rotor and bridges styled after the 69355, or a slim clone with a closed or partially open caseback. Each trades something away.
- 7750-based builds: proven, easy for any watchmaker to service, robust chronograph feel. Thicker than the original, which pushes the caseback off the wrist slightly.
- Decorated 7750: same reliability with better visuals through a display back. The decoration is cosmetic, so do not pay a premium for it unless the caseback is genuinely open.
- Slim clones: closer to the original thickness but harder to service and less tolerant of daily chronograph use.
For most buyers the decorated 7750 is the balance point. If you plan to run the chronograph often, favor the proven base over the thin one.
Criterion 4: Crystal, caseback, and water resistance
A domed sapphire with a subtle inner anti-reflective coating transforms the dial. Flat mineral glass with a heavy blue tint does the opposite. Ask whether the crystal is sapphire and check the edge of the dome for a visible step where it meets the bezel.
- Pros of a proper display back: the movement decoration and rotor engraving become part of the experience.
- Cons: a poorly finished back is worse than a solid one, and every display back is one more seal to leak.
Treat any water resistance claim as decorative unless the watch has been pressure tested. Splashes and rain are fine. Swimming is not.
Criterion 5: Strap and hardware
Alligator-pattern leather with a signed pin buckle is standard, and the strap is where factories cut corners most often. Stiff, glossy, plastic-feeling leather makes a good case look cheap. A quick swap to a quality aftermarket strap in the correct 20 mm width is the cheapest upgrade you can make, and it changes how the watch reads more than any other single purchase.
Which tier fits which buyer
- First replica, wearing it to the office: mid tier with a decorated 7750, upgraded strap. Best balance of look and serviceability.
- Collector who handles watches closely: upper tier case and dial, accept the movement premium. You are paying for finishing, not timekeeping.
- Weekend wear, occasional use: a basic 7750 build is honest value. Do not overspend on decoration you will not see.
Red flags before you commit
- Stock photos only, with no real images of the actual unit under natural light.
- No answer on movement type or crystal material.
- Pushers that feel gritty or a crown that wobbles when pulled.
- Subdial hands that reset to different positions when you zero the chronograph.
- No return window. Always confirm the return terms in writing first.
The short version: judge the case and the subdials first, the movement second, and the strap last, because the strap is the one thing you can fix yourself.