Short answer
The IW371613 is a member of the IWC Portugieser Chronograph line, reference family 3716. Counterfeit copies exist. They show up in case thickness, movement finish, case back engraving, and paperwork. Check those four points before you pay.
What the IW371613 should be
IWC introduced the 3716 family in 2020 as the replacement for the 3714. The steel version measures 41.0 mm across and 13.1 mm thick. Water resistance is 3 bar. The movement is calibre 69355, an automatic chronograph with a 46-hour power reserve and a beat rate of 28,800 vibrations per hour. The dial has two registers: small seconds at 6 o'clock and a 30-minute counter at 12 o'clock. The date sits at 3 o'clock. The ref. 3716 has a sapphire crystal and a sapphire display back.
IWC lists the dial color, hands, and strap for each reference number on its own site. This guide does not assume a dial color for the IW371613. Confirm the exact variant first, then judge the watch.
Case and dimensions
Measure the case with calipers, not by eye. Fakes run thick. A copy that reads 14 mm or more at the case flank is not a 3716 case. Check the lug shape and the polished bevel between the brushed top surfaces. Check the crown for the IWC probe engraving. Pushers should start, stop, and reset with a short, firm travel.
Dial and hands
- Subdial positions: 6 o'clock and 12 o'clock, on the vertical axis of the crown.
- Printed text: sharp edges, no bleeding into the lacquer.
- Hands: correct length, no burrs at the tip, correct polish contrast.
- Date window: cut clean, with the numeral centered.
Case back and serial number
The case back carries the reference number and a serial number. Engraving is deep and even. Fakes use shallow laser marking or a sticker. The reference on the back must match the reference on the papers. If the back reads 3714 and the listing says IW371613, the case back is not original to that watch.
Movement
A display back lets you see the rotor and bridges. Genuine calibre 69355 shows striped bridges, circular graining on the plates, and clean screw slots. Copies often use an Asian 7750 copy or a quartz movement under a decorated plate. A quartz movement has a ticking seconds hand. The 69355 sweeps.
Papers and IWC registration
Genuine watches ship with a warranty card and a serial number that can be registered with IWC. Ask the seller for the serial before payment. Ask IWC or an authorized dealer to confirm it. A watch that cannot be registered, or whose serial belongs to a different reference, is not a safe buy.
Price as a check
A steel Portugieser Chronograph 41 sells new for several thousand US dollars. Any IW371613 offered for a few hundred dollars is a replica, not a mislabeled genuine watch. Treat the price as data, not as proof.
Where to verify
IWC service centers and authorized dealers authenticate watches. Independent watchmakers with IWC parts accounts can open the case and check the movement. Get the result in writing before a return window closes.