Short answer
A fake IW5451-10 fails on three points: the dial printing, the caseback engraving, and the movement. The reference belongs to the IWC Portuguese Hand-Wound line. The real watch uses a 44 mm case, sapphire front and back, and the 98295 hand-wound calibre. Replicas copy the outline and miss the details below.
What the reference is
IWC built the Portuguese Hand-Wound as a large, plain dress watch. Reference 5451 carries a small seconds hand at 6 o'clock, applied numerals, and a railroad minutes track. There is no date. IWC's product page lists case size, crystal type, and calibre for each dial variant. Read that page before you compare a watch to listing photos.
Two grades of fake
Sellers list this reference in two grades. The low grade has a printed dial and a plated case. The higher grade copies the case shape and dial layout and uses a clone of the Unitas 6498 movement. The 6498 places its small seconds hand at 6 o'clock, which is why it fits this dial. The 6497 does not, so a fake with a sub-dial at 9 o'clock is the wrong base. Ask which calibre sits inside before you talk about finish.
Dial checks
- Numerals: applied and polished on the real dial. Fakes use glued or printed numerals with soft edges.
- Logo: sits under 12. Check letter shape and print depth with a loupe.
- Minutes track: thin and even on the real part. Fakes show thick lines and gaps at the hour marks.
- Sub-seconds hand: sits close to the dial. A long exposed pivot is a fake sign.
- Date: this reference has none. Any date opening is wrong.
Case and caseback
Check the crown first: signed, with a defined grip. Check the lugs: sharp bevels on a real case, rounded edges on a fake. The caseback has a sapphire window and an engraved reference number. Engraving on a fake sits shallow and the font runs wide. The digits read 5451 with a suffix for the dial variant. Ask for a photo of the engraving between the lugs.
Movement checks
The 98295 shows a wide bridge plate, striped finish, and blued screws. Look at the balance cock and the regulator index. A 6498 clone shows another bridge shape, a plain finish, and a shock spring of a different design. Ask for a photo with the caseback open. A seller who refuses a movement photo carries risk.
Price signals
Genuine 5451 examples trade in the thousands of US dollars. Replica listings sit in the low hundreds. A price between those two bands is a warning. Check sold prices on marketplaces, not asking prices. Box and papers add value to a real watch and add nothing to a fake.
Questions to send a seller
- Which calibre is inside, and can you send a clear photo of it?
- Is there a service record, and who did the work?
- What is the case weight and diameter in millimeters?
- Can you photograph the reference engraving and the crown signature?
One point stays unverified: IWC does not publish serial ranges by year for this reference in public. Treat any seller claim of a third party serial lookup as unproven.