The fake Portofino moon phase 35 is a replica of IWC's small-cased Portofino Automatic Moon Phase, a 34 mm to 37 mm family that sellers often list as 35 mm. The genuine watch runs IWC calibre 35800 with a geared moon phase disc inside a 37 mm steel case. Replicas sold under this name rarely copy that mechanism, so the moon disc is the first thing to inspect.
What does "Portofino moon phase 35" refer to?
"35" is a seller label, not an IWC reference number. IWC's catalog for this line lists a 34 mm Portofino Automatic and a 37 mm Portofino Automatic Moon Phase, with no 35 mm moon phase model.
Because the case is small, replica factories have less room to hide a stacked movement module. That makes size and thickness unusually useful checks on this model.
Genuine specs to compare against
- Case: 37 mm stainless steel, roughly 9 mm thick, slim lugs
- Movement: IWC calibre 35800 automatic, about 42 hours of power reserve, 28,800 vibrations per hour
- Moon phase: aperture at 12 o'clock, advanced by a gear train across roughly 29.5 days
- Crystal: sapphire, with display case backs on some editions
- Strap: alligator leather on many references, typically 18 mm at the lugs
How do replica Portofino moon phase watches fake the moon?
Most replicas either freeze the moon or drive the disc from the hour hand, so it completes a full cycle in 24 hours instead of 29.5 days. Watch the aperture for two minutes, because a real moon phase creeps almost imperceptibly.
Cheaper examples use quartz movements with a printed disc that jumps once a day. Better automatic replicas pair a clone of an ETA 2824 or a Sea-Gull automatic with a bolt-on moon phase module.
What to inspect on a replica
- Thickness: a stacked module usually pushes a 37 mm replica 1 mm to 2 mm past the genuine profile.
- Moon aperture: the opening should sit on the vertical centerline with even spacing to the indices.
- Dial printing: lettering weight, applied index polish, and the detail of the moon disc's stars and figure.
- Case back: engraving depth, reference number, and font.
- Strap: embossed cowhide compared with genuine alligator grain and stitching.
Why is the moon phase hard to copy well?
A moon phase needs a reduction gear that turns a disc once every 29 days, 12 hours, and 44 minutes. IWC advertises a deviation of one day in about 122 years for this display, which demands tight tolerances inside a small case.
Replica modules cut corners on that gearing, so they run fast, run slow, or stall. A stalled disc is the most common failure reported on small-case moon phase replicas.
Are fake Portofino moon phase watches legal to buy in the US?
No. Counterfeit branded watches infringe trademarks, and importing them violates 19 U.S.C. section 1526. U.S. Customs and Border Protection can seize shipments, and sellers face civil and criminal penalties.
FAQ
Does a replica Portofino moon phase track the real lunar cycle?
Almost never. Most units advance the disc once a day or once every 24 hours, so the moon drifts out of sync within days.
What size is the genuine Portofino moon phase?
IWC builds this line in 34 mm and 37 mm cases. A listing that says 35 mm is using a marketing size, not a factory reference.
What movement is inside these replicas?
Typical builds use a quartz caliber or a Chinese automatic with a bolt-on moon phase module. Neither matches calibre 35800's finishing, beat rate, or power reserve.