Short answer
IW371421 is an IWC reference inside the Portugieser Chronograph block, the IW3714xx numbers. A counterfeit of that reference is a watch built outside IWC and stamped with the same number. Most copies sold as IW371421 use a Valjoux 7750-type chronograph movement or a quartz module, a 40 mm to 42 mm case, mineral or single-coated glass, and stamped hands. A genuine IW3714 case measures 40.9 mm across, uses sapphire crystal with anti-reflective coating on both faces, and carries factory engraving on the back.
What the reference number covers
IWC groups references by model family. The IW3714 block covers the Portugieser Chronograph with two subdials: small seconds at 6 o'clock and chronograph minutes at 12 o'clock. Steel, gold, and boutique variants sit in the same block. IWC does not publish a full archive of every dial and strap combination, so one number can return several listings with different dials. Confirm the exact variant with IWC or an authorized dealer before you treat a photo as proof.
Case and dial checks
- Diameter. Genuine IW3714 cases measure 40.9 mm. Copies measure 40.0 mm or 42.0 mm because the maker reuses a stock case.
- Crystal. Genuine sapphire has anti-reflective coating inside and outside. Copies show a blue or purple wash from one face, or scratch faster than sapphire.
- Subdials. Small seconds sits at 6 o'clock, chronograph minutes at 12 o'clock. A copy with three subdials or a 9 o'clock register does not match the reference.
- Printing. Dial text sits under the crystal layer on genuine pieces. Raised or flaking text is a copy tell.
- Hands. Feuille hands have a leaf profile with a sharp centre ridge. Stamped copies show a flat or blunt profile.
Movement and case back
Earlier IW3714 watches ran calibre 79350, a Valjoux 7750 base modified by IWC. Current production uses the 69355 family, which IWC lists as in-house. Both beat at 28,800 vibrations per hour, or 4 Hz. That is eight steps per second on the running seconds hand. Quartz copies tick once per second. The case back carries the reference, the case serial, and IWC markings cut into the metal. Laser-printed or shallow etched text on the back points to a copy. Water resistance on the genuine watch is 3 bar.
Market signals
Used Portugieser Chronograph steel watches trade from roughly USD 5,000 to USD 8,000 depending on metal, box, and papers. Listings at USD 300 to USD 800 for a new IW371421 are copies. Sellers who ship from a warehouse, use stock photos, and hide serial numbers move most of the 1:1 clone stock.
Verification steps
- Ask for the case serial and reference from the back, then check them against IWC service records.
- Measure the case with calipers. Expect 40.9 mm, not 42 mm.
- Time the seconds hand. Eight beats per second, not one.
- Ask for a movement photo through the display back. Look for IWC engraving on the rotor and striped bridges.
- Compare the asking price with sold listings. A 90 percent discount is a copy.