Quick answer
The IW3717 is the reference family for the IWC Portofino Chronograph: a 42 mm stainless steel chronograph built around the ETA/Valjoux 7750 architecture. Replica versions are common because the dial is plain and cheap to print. Most copies get the outline close and the details wrong. The case runs 1 to 2 mm thicker than the original, the subdials sit too far apart, and the chronograph pushers feel soft. When you compare listings, judge the movement first, the case thickness second, and the dial print third.
What the genuine reference is
The Portofino Chronograph IW3717 family uses a 42 mm case at roughly 13.5 mm thick, with sapphire crystal front and back on most versions. The movement is IWC caliber 79320, a modified 7750 running at 28,800 vph with about 44 hours of power reserve. Layout is standard 7750: running seconds at 9, 30-minute counter at 12, 12-hour counter at 6, and day/date at 3. Water resistance is modest, so no one is diving with it.
That simple, legible face is exactly why the reference gets copied. There is little guilloche, no skeleton work, and no exotic material to reproduce.
Where replicas usually miss
- Thickness. An Asian 7750 clone plus a thick caseback spacer adds 1 to 2 mm. The watch sits high on the wrist.
- Subdial spacing. The three registers drift outward or inward from the genuine positions, which throws off the whole face.
- Crystal. Many copies ship with mineral glass or a coated sapphire that shows a blue or purple cast.
- Date wheel. Font weight and alignment rarely match. Cheap builds use printed discs that sit off-center.
- Caseback text. Reference numbers are stamped or laser-etched shallow, not engraved deep with clean edges.
- Pushers. Genuine pushers have a short, crisp travel. Copies feel spongy or need a hard press.
How to inspect a replica IW3717
- Ask the seller which movement is inside and request a photo of the caseback with the rotor visible.
- Measure the case thickness with calipers. Anything past 14.5 mm is a giveaway.
- Start the chronograph and watch the center sweep hand. It should move in small, steady steps, not jump.
- Let the chronograph run for two minutes, then reset it. The hand must snap back to zero and stay there.
- Check the three subdial hands for alignment at the 12, 6, and 9 positions before you pay.
- Look at the date window under a loupe. The numeral should be centered and level with the frame.
- Weigh the head on a kitchen scale. A steel case on a real 7750 lands near 90 grams.
- Compare the caseback reference stamp to photos of the genuine piece from the maker's own site.
Red flags in listings
- Only stock photos, no real images of the actual watch.
- Price far below the rest of the market for the same movement.
- Claims of "1:1" or "same factory" with no movement name.
- No return window, no payment protection, and pressure to pay by wire.
- Seller refuses a video of the chronograph running and resetting.
Legal and import realities
Counterfeit watches are illegal to sell or import in the United States. US Customs and Border Protection can seize shipments, and trademark owners can pursue civil claims against sellers. Buying a replica is not a neutral transaction: it carries financial and legal exposure that a genuine pre-owned watch does not. If a listing promises guaranteed delivery through customs, treat that as a warning sign rather than a feature.
Questions to send a seller
- What exact movement is installed, and who made it?
- What is the measured case thickness and diameter?
- Can you send a video of the chronograph starting, running, and resetting?
- What is the return policy, and who pays return shipping?
- Is the crystal sapphire or mineral, and what coating is on it?