Short answer
"Fake Portofino moon phase 35" is buyer shorthand for a replica of IWC's Portofino Automatic Moon Phase, usually listed with a 35mm case. That size label is the first thing to question. The real reference most sellers copy, the Portofino Automatic Moon Phase 37, measures 37mm across and about 11mm thick, so a "35" listing is either a smaller case the factory actually built or a number a seller typed without measuring. Ask for calipers on the case, not a wrist photo.
What the moon phase on these copies really is
A working moon phase is a geared disc. It turns a tiny amount each day and finishes one full cycle in about 29.53 days, which is why the moon drifts a day or so off the sky over a few years. Genuine Portofino moon discs carry a night sky with a gold or silver moon, and the disc creeps forward slowly enough that you cannot watch it move.
Plenty of replicas skip that gear train and drop in a day and night disc instead. Those flip between a sun and a moon every 12 or 24 hours. It looks convincing in a product photo and falls apart the moment you own it. The test takes one day: set the disc to a full moon, note the position, wait 24 hours, then look again. A real moon phase moves a sliver. A fake swaps the whole picture or stays still.
Movement, feel, and noise
Under the caseback you will usually find a Miyota 9015, a Seiko NH-series, or a Chinese automatic with a moon phase module bolted on. The module is where the money goes, and it is also where corners get cut. Wind it slowly and listen. A gritty crown, a rotor that rattles when you tilt your wrist, or a moon disc that changes while you set the time all point to a module and a base movement fighting each other.
Case and dial checks
- Measure the case, lug to lug, and thickness yourself. 37mm wide and roughly 11mm thick is the target on the reference most copies chase.
- Look at the moon aperture at 6 o'clock. Edges should be crisp, with no printed outline or sticker showing through.
- Check the indices. Applied and polished on better builds, flat printed paint on cheap ones.
- Read the dial text. Uneven letter spacing on the brand name and a thin, pale "automatic" line are common.
- Turn the watch over. A display back with a decorated rotor belongs on some references and not others, so match it to the exact model you are comparing.
- Tap the crystal. Sapphire gives a flat click, mineral sounds dull. Scratches after a week means mineral.
Price tiers
Under $100 you get a printed moon that never moves. Around $150 to $350 you get a decent case, sapphire, and a moon disc that cycles correctly. Above that, you pay for finishing, a better module, and closer dial printing. None of it turns a replica into a genuine watch, and resale value stays near zero.
Questions to send a seller
- What is the measured case diameter in millimeters?
- Which movement and which moon phase module?
- Does the moon disc advance every day or flip every 24 hours?
- Crystal material, and is the caseback solid or display?
- Water resistance rating, and was it tested?
Bottom line
The moon phase is the whole point of this watch, so judge the copy on that alone. If the disc does not track the lunar cycle, the rest of the watch does not matter. Confirm the case size in millimeters, get the movement name in writing, and treat any 35mm listing as unverified until someone measures it.