Short answer
A replica IW371747 is a copy of the IWC Portugieser Chronograph ref. 3717, a steel chronograph that IWC sold from about 2007 to 2015. Copies come in two groups. Automatic versions use a Chinese copy of the Valjoux 7750 layout. Quartz versions cost less and show a jumping chronograph seconds hand. Prices run from about $90 for quartz to $600 for the top automatic tier. Case size, subdial position and dial print decide the quality of a copy.
Genuine specs are the yardstick: 40.9 mm steel case, about 12 mm thick, sapphire crystal, calibre 79350, 44 hour power reserve, 30 m water resistance, running seconds at 6 o'clock, chronograph minutes at 12, date at 3.
What the reference number means
IWC uses a six digit reference scheme. IW371747 sits in the 3717 block. The 3717 line followed the 3714 Portugieser Chronograph and kept the 40.9 mm case. Dials came in black, silver and slate. IWC no longer lists ref. 3717 in its current catalog, so buyers work from archived spec sheets and secondary market photos.
Movement inside a replica
Automatic copies use the Asian 7750 layout. That layout puts chronograph minutes at 12 and running seconds at 6, which matches the 79350. The seconds-at-6 gear train adds load on the Asian 7750 and stutter of the 6 o'clock hand is a known fault. Quartz copies move the chronograph seconds in one second steps. Ask for a movement photo and a short video of the chronograph start, stop and reset before payment.
Checks before you pay
- Case diameter: 40.9 mm, measured with calipers.
- Subdial centers: 12 and 6, on the vertical axis of the dial.
- Date window: at 3, framed, with a font close to the IWC print.
- Dial text: "IWC" and "Schaffhausen" thin, with sharp edges.
- Hands: leaf shape, correct length, rose gold tone on some dials.
- Caseback: screw-down, engraved with a reference and serial block.
- Weight: a steel case of this size on a leather strap sits under 100 g.
What copies get wrong
Four faults show up on most replica IW371747 units. Subdial hands stop short of the hash marks. Date digits sit wide and flat. The rotor is louder than the 79350. The case profile is the fourth: the 3717 has a slim bezel and a curved lug, and copies with a flat lug sit wrong on the wrist. Dial print thickness is the easiest tell in photos.
Cost and service
Automatic copies sell for $250 to $600. A service on the Asian 7750 costs $80 to $150 at an independent watchmaker and takes two to four weeks. Quartz copies need a battery change every two to three years. No replica holds value. Resale runs at half the purchase price or less.