Short answer
A genuine IW371701 is a 42 mm stainless steel chronograph with a 14.6 mm thick case, a 21 mm lug width, and caliber 79320 inside. Fakes miss at least one of those numbers. Measure first, then inspect the subdials, the crystal, and the movement. No single check proves a watch is real. Three or four checks together do.
Reference facts to verify
- Reference: IW371701, also written 3717-01.
- Production run: 2006 to 2012. The IW3777 family replaced it.
- Case: stainless steel, 42 mm wide, 14.6 mm thick.
- Movement: IWC caliber 79320, based on the Valjoux 7750, 25 jewels, 28,800 vph, about 44 hours of power reserve.
- Dial: black, day and date window at 3 o'clock.
- Subdials: 30 minute counter at 12, 12 hour counter at 6, running seconds at 9.
- Crown: screw-in. Water resistance: 60 m.
- Strap: 21 mm between the lugs.
1. Measure the case
Use a caliper. A genuine 3717 reads 42.0 mm across the case, crown excluded, and 14.6 mm thick. A quartz fake is thin, often near 11 mm. A fake built on a 7750 clone runs thick, often past 15.5 mm. Case width errors of 1 mm to 2 mm show up on many replicas.
2. Check the subdial layout
The running seconds hand sits at 9 o'clock. The 30 minute counter sits at 12. The 12 hour counter sits at 6. A quartz fake moves the seconds hand to the center pinion or to 6 o'clock. Look at which subdial ticks once per second. A ticking hand at 9 means quartz. A sweeping hand at 9 means mechanical.
3. Look at the movement
Remove the case back. Caliber 79320 is a Valjoux 7750 base. The rotor carries IWC engraving and the caliber number. A blank rotor, a Miyota stamp, or a jewel count other than 25 points to a fake. A quartz movement under a screw-down case back is a clear sign.
4. Inspect the dial and crystal
Dial print on a genuine watch is sharp, level, and even in weight. Fakes show thick strokes, blurred edges, and uneven spacing between the logo and the text below it. Dial text placement changed between the 3717 and the later 3777, so compare against a photo of a genuine 3717, not a 3777.
The crystal is sapphire with an anti-reflective coating on both faces. It shows a blue tint at an angle and near zero reflection from straight on. A mineral glass fake reflects light with a yellow or white cast. A sapphire fake often has coating on the outer face alone.
5. Check the crown and pushers
The crown screws down and seats flush with the case. The two chronograph pushers are push type, not screw-down. Start, stop, and reset should feel crisp. The chronograph hands must snap back to zero in one move. A wobble, a slow return, or a hand that lands at 12:01 points to a cheap movement.
6. Read the case back
The case back is solid steel. It carries the reference number and a serial number. Engraving on a genuine watch is cut deep with clean edges. Laser etching and shallow stamping are common on fakes. Serial numbers are not in a public database, so a number alone proves nothing. IWC can confirm a watch during service or authentication.
7. Price and availability
The 3717 stopped production in 2012. A new old stock 3717 sold as a current model is a warning sign. Secondary market prices for a genuine 3717 sit in the thousands of US dollars. A price far under market, or a seller who refuses a case back photo, is enough reason to walk away.
What a photo cannot show
Photos hide case thickness, crystal coating, and movement finish. Ask for a side profile shot with calipers, a movement shot with the rotor visible, and a serial number photo. If a seller will not send those three images, treat the watch as unknown.