Short answer
IW545104 is a reference number for an IWC Portugieser Hand-Wound watch. A copy sold under that number has to match a round steel case, a dial with Arabic numerals and a rail-track minute scale, leaf hands, a small seconds subdial at 9 o'clock, and a hand-wound movement under a sapphire caseback. If the watch in the photos has a date window, a center seconds hand, or a rotor visible through the back, it does not match the reference.
How IWC reference numbers work
IWC builds reference numbers in blocks. The IW prefix marks the brand. The digits that follow split into a family code and a variant code. The family code points to a case and movement group. The final two digits fix the variant: case metal, dial color, and strap. Two watches numbered one digit apart can share a movement and differ in look and price.
The practical result: IW545104 names one build, not a range. Confirm the variant on IWC's product page before you compare any copy to it.
Parts a replica has to match
Use the IWC catalog page for the exact variant as the baseline. It lists case diameter, thickness, metal, dial, crystal, strap, and movement. Measure the copy against those numbers.
- Case: diameter and thickness from the spec sheet. Portugieser Hand-Wound cases sit in the 42 mm to 44 mm range, so a 40 mm copy reads small on the wrist.
- Dial: Arabic numerals, a printed rail-track minute scale, and a small seconds subdial at 9 o'clock. Numeral shape and print weight are the parts copies get wrong.
- Hands: leaf shape and polish. Compare against reference photos at the same angle.
- Movement: hand-wound. A rotor under the caseback means the copy runs an automatic movement, which is a mismatch.
- Caseback: sapphire display back with engraving. Check text, font, and engraving depth.
- Crown and strap: compare crown diameter and strap width in millimeters with the spec.
Movement check
The reference runs on a hand-wound IWC calibre. Copies use third-party movements, so beat rate and power reserve will not match IWC's listed figures. Wind the watch a full turn count, set it down, and time how long it runs. Compare that figure with the power reserve on IWC's page for the reference.
Gaps a copy shows
Movement decoration, engraving sharpness, and rate stability over weeks are the usual shortfalls. IWC does not service or authenticate counterfeit watches, so there is no repair path through the brand.
Price and supply
Copies sell in tiers set by sellers. No published price list exists. Price moves with movement type, case finish, and dial accuracy. Water resistance claims from sellers come with no test data. There is no serial number registry and no warranty from the brand.
Legal status in the US
Counterfeit watches are illegal to import and to sell in the United States. U.S. Customs and Border Protection can seize shipments at the border. Trademark owners can record their marks with CBP to block entry. Buying from an overseas seller carries seizure risk. Selling carries civil and criminal exposure.
Bottom line
Match the copy to IWC's listed specs for the exact 5451 or 5454 variant. Then check three items: small seconds at 9 o'clock, a hand-wound movement with no rotor, and a case diameter that matches the spec sheet. Everything else is a detail you can compare against reference photos.