Short answer
A replica Blancpain moon phase is worth buying only when the moon disc actually tracks the lunar cycle and the case stays thin. Those two things decide everything else. A moon phase is a small aperture on a dress watch, so if the aperture and the disc look wrong, no amount of good bracelet or box presentation saves it.
Why the moon phase is the hardest part to fake
A real moon phase runs off a 59-tooth wheel that advances one tooth per day, which gives a full cycle in 29.5 days. Cheap reps skip the gearing and wire the disc to a 24-hour wheel instead, so the moon flips from light to dark once a day. You can catch that in about ten seconds: set the watch to noon, note the moon, wait twelve hours or reset forward, and look again. If it moved half a circle, it is a day and night disc wearing a moon phase costume.
On a proper one the moon creeps forward a little each day, the way the genuine article does. Expect about one day of drift every two and a half years. That is normal for the 59-tooth setup and the real Blancpain behaves the same way.
Dial and print checks
- The aperture: on the Villeret Quantième Complet the moon sits in a window at 6 o'clock with a blued serpentine date hand sweeping an outer track. Simpler Villeret moon phase models use a round or gently arched window.
- Moon art: dark blue sky, a moon with a face, small scattered stars. A flat black sky or oversized stars signals a low-tier dial.
- Print: the Blancpain script, then Villeret, then the automatic line. Compare serif weight on the B and the gap between words. Rep dials often space the text a touch wide.
- Markers: applied and polished on the better tiers, printed flat on the cheap ones.
Case and thickness
Villeret cases are slim, and that is the hard part for replica makers. A moon phase module adds height, so many reps wear thicker than the roughly 11mm to 12mm of the original. Ask for a side profile photo next to a ruler before you pay. On the wrist, an extra 2mm turns a dress watch into something that snags a shirt cuff.
Width matters too. The Quantième Complet is a 40mm piece, the plainer Villeret moon phases run smaller, and anything listed at 43mm under that name is a fantasy size.
Movement tiers
- Quartz with a cosmetic moon: cheapest option, disc runs on a 24-hour cycle or does not move at all. Skip it.
- Chinese automatic with a moon phase module: the sweet spot. Real 29.5-day disc, and on complete calendar versions the day, date and month all work. Finishing is plain and the rotor is audible, but the complication does its job.
- Swiss ETA base with an added module: closest feel to the original, biggest price jump. Only worth it when the dial and case are already right.
Setting it without breaking it
Never change the date, month or moon between about 9 p.m. and 3 a.m. The calendar gears are meshed then and you can strip teeth. Pull the crown to the time-setting position, move the hands to 6:30, set the calendar, set the moon to the last known full moon date, then set the time. The same rule applies to the genuine watch, which is why it belongs in the manual.
What I would check before paying
- A short video of the moon disc advancing over a full day
- Side profile shot for thickness
- Macro of the dial print and the edge of the aperture
- Confirmation that day, date and month each set independently
- Water resistance claim. Treat it as splash only, these are dress watches.
Get those five items and you will know more about the watch than most sellers do.