Short answer
IWC does not list an IW371772 in its public reference records. The Portugieser Chronograph numbers IWC publishes sit in the 3714 and 3716/3717 groups. A watch offered as an IW371772 carries a reference that does not match a catalog entry. Treat that as a first warning. Ask the seller for the reference stamped on the caseback and compare it to the papers.
How reference numbers work
IWC reference numbers follow a pattern. The first digits name the family and case type. The last digits name the dial and strap variant. A number ending in 72 has the right shape, so a copy can take a real number and swap two digits. The pattern alone proves nothing. The stamped caseback and the IWC catalog settle the question.
Dial checks
- Subdials sit at 12 and 6. The top subdial counts chronograph minutes. The bottom subdial runs the seconds.
- Numerals are applied, not printed. Run a fingernail over an edge. A printed copy sits flat.
- Dial print sits under a lacquer layer. Text on a fake sits on top and looks raised.
- The date window sits at 3. Cut edges are sharp on the real part. Rounded corners point to a copy.
- Hands are leaf shaped and thin. Thick hands with blunt tips are wrong.
Case, crystal and caseback
Real Portugieser cases are machined from steel or gold and finished by hand. Lugs have crisp bevels. The crystal sits flush with the bezel. A copy shows a lip at the edge and soft polishing on the lugs.
The caseback carries an engraved reference, a serial number and the IWC mark. Engraving depth is even. Laser etching on a copy looks shallow and gray. The serial on the caseback must match the serial in the warranty booklet.
Movement
Portugieser Chronograph watches use IWC caliber 79320, a modified Valjoux 7750. It beats at 28,800 vibrations per hour and runs about 44 hours on a full wind. The rotor winds in one direction. The chronograph pushers feel firm and reset with a snap. A copy built on a cheap chronograph module feels soft, and the seconds hand jumps when the chronograph starts.
Price, box and papers
A new Portugieser Chronograph retails in the high four figures to low five figures in US dollars. Used examples trade below retail by a margin set by age and condition. An offer far under that range is a signal. Boxes, booklets and warranty cards are easy to print. Check the serial against IWC service records, or pay a watchmaker to open the case.
Steps before you buy
- Ask for a clear photo of the caseback engraving and the serial.
- Compare the reference number to the IWC catalog.
- Have a watchmaker check the movement and the rotor finish.
- Walk away if the serial is missing or appears on more than one listing.
If the seller cannot show a caseback photo, stop. No photo, no sale.