Short answer: IW938738 is a listing code used by replica sellers, not a documented IWC reference, so the watch behind the code has to be judged on its own parts. The top pick for most buyers is a mid-tier build with a working chronograph movement, confirmed case dimensions, and macro photos of the movement and dial sent before payment. The criteria that decide the purchase are reference identity, movement type, dial printing, case and caseback finish, bracelet hardware, and the quality of seller evidence.

What the code IW938738 actually is

IWC publishes references in family blocks with the IW prefix and six digits, for example the IW37 block used for Portugieser chronographs and the IW50 block for Portugieser automatics. The number 938738 does not sit in a block that maps to a documented model, so it reads as a seller SKU rather than a factory reference. That alone is not proof of a bad watch. It does mean the listing title tells you nothing about which watch arrives, and the photos have to carry the whole case.

• Pros of a SKU: a stable code lets you compare the same build across shops and ask each seller for photos of the exact unit.
• Cons of a SKU: it guarantees no model, so two sellers can ship different watches under the same number.

Check 1: Reference identity

Ask the seller which real model the build copies, then compare that model's published specs: case diameter, thickness, lug width, crystal shape, subdial positions. If the seller cannot name the source model, or the numbers drift by more than a millimeter, the build is a generic case with a familiar dial.

• Pros: a named source model gives you a spec sheet to check against and a fair expectation for size and weight.
• Cons: sellers sometimes name a model loosely, so verify the specs yourself rather than trusting the description.

Check 2: Movement and subdial function

Most chronograph replicas in this class run a 7750-pattern automatic, which places running seconds at 9 and the minute counter at 12. Ask for a short video that starts the chronograph, lets it run, and resets to zero. On cheap builds the subdials are decorative and never move, or a quartz module drives the hands. A wobbling rotor sound and a sweeping seconds hand point to a mechanical movement; a ticking hand points to quartz.

• Pros: a video with a working chrono and a clean reset rules out the worst builds in one step.
• Cons: a clip can be filmed on a different unit, so ask for a dated card or a live call.

Check 3: Dial, printing and hands

Zoom in on the indices, the date window, and the text at 6 o'clock. Applied metal indices should sit level with clean edges, the date font should match the source model, and the printing should be crisp under magnification rather than thick or doubled. Lume that looks unevenly filled or sits above the frame is a common tell on cheaper builds.

• Pros: dial photos are the easiest evidence to collect and the hardest for a weak build to fake.
• Cons: phone photos hide flaws, so ask for macro shots under daylight, not studio light.

Check 4: Case, crystal and caseback

Confirm sapphire rather than mineral crystal, check that the caseback engraving is deep and centered, and ask for the measured thickness with calipers. Thin cases on a 7750-pattern movement often mean a decal caseback or a movement swap. Serial and reference engravings between the lugs should be cut, not laser-printed in a flat font.

• Pros: caliper photos and caseback macros expose most mislabeled builds before money changes hands.
• Cons: few sellers own calipers, so an unwillingness to measure is itself information.

Check 5: Bracelet, clasp and hardware

Solid links, a firm clasp action, and end links that sit flush against the case separate mid-tier builds from entry ones. Ask how many removable links ship and whether the clasp carries the correct engraving depth. A rattling bracelet on an otherwise good watch is the cheapest thing to fix and the easiest thing for a seller to hide.

• Pros: hardware is visible in hand and easy to judge in a short video.
• Cons: sellers often photograph the watch head only, so request bracelet shots on purpose.

Check 6: Seller evidence and terms

Look for a return window measured in days, a payment method with buyer protection, and tracking that starts before the stated ship date. Counterfeit goods can be seized at import, so confirm who absorbs a customs loss in writing. Vague answers on returns or payment are the strongest reason to walk away from a listing, more than any flaw in the watch itself.

• Pros: a written return policy turns a risky purchase into a testable one.
• Cons: many shops treat returns as a favor, which leaves you holding the loss.

Price tiers and what 1:1 claims mean

Entry builds cut cost on the movement, crystal, and bracelet. Mid-tier builds spend the money on a working chronograph movement and better dial printing. Top-tier builds add closer case geometry and finishing, but no replica is a 1:1 copy, and any listing that promises that is overselling. Judge the watch by the six checks above, not by the tier label.

Who should buy, and who should walk

Buy the mid-tier build if you want a working chronograph, a sapphire crystal, and a bracelet that does not rattle, and if the seller will send dated macro photos plus a chrono video. Walk away if the seller cannot name the source model, will not show the movement, or offers no return window. If you want brand paperwork, service history, or resale value, no replica under any SKU will deliver that, and a genuine reference is the only route.