Quick answer
A replica Villeret moon phase is a calendar watch with a curved aperture at 6 o'clock holding a printed disc with two moons. The feature you are paying for is a disc that advances one position per day, roughly every 24 hours, and completes a full turn in about 29.5 days. Many cheap copies instead fit a 24 hour day and night wheel that spins once a day, which makes a full lunar cycle read as one day. Check that single point first, then check print quality, date alignment, and corrector function.
How the complication works
On the original Blancpain Villeret complete calendar, the moon disc sits under a shaped aperture cut into the dial and is driven from the calendar train. A finger on the hour wheel pushes the disc forward one tooth each day. The gearing is built around the synodic month, which runs about 29.53 days, so a simple disc with 59 teeth covers two lunar cycles before it needs a correction of roughly one day every two and a half years. A copy that gets this right will drift the same way. A copy that does not will show a moon in the wrong phase within a week.
Pre-purchase checks
Run these checks in order. Bring a loupe or use your phone on macro mode.
- Photograph the aperture, then photograph it again 24 hours later at the same time of day and compare the disc position.
- Confirm the disc moved by one half position, not a full rotation.
- Inspect the moons and stars for pixelation, soft edges, or two moons that are not identical in shape and size.
- Check the aperture edge for a clean bevel and no visible burrs or tool marks.
- Push each recessed corrector and confirm it clicks and returns without sticking.
- Set the watch to midnight and watch the day, date, and month change inside a 90 minute window.
- Verify the moon disc and the date wheel do not jam when both change on a shared night.
- Wind the movement and note the power reserve with a timegrapher if you have one.
- Ask whether the case back gasket and crown seals were tested, and confirm the stated water resistance before you trust it near water.
Setting the moon phase in the right order
The safe part of the cycle to use the correctors is between roughly 6 in the morning and 4 in the afternoon, when the calendar train is disengaged. Pushing a corrector during the change window can bend a finger or strip a tooth.
- Wind the crown about 20 turns to give the movement full torque.
- Pull the crown to the time setting position and move the hands to 6:30, keeping the date off its change point.
- Use the corrector at 8 o'clock to advance the day to the correct weekday.
- Use the corrector at 4 o'clock to advance the date to the day before the target date.
- Use the corrector at 10 o'clock to advance the month.
- Push the crown home and sweep the hands forward past midnight until the date and day click over to the correct value.
- Look up the last full moon date and count the whole days between then and your target date.
- Press the moon corrector once for each of those days, watching the two moons step through the aperture.
- Stop when a moon is centered under the opening, which represents a full moon.
- Set the hands to the correct time, push the crown in, and check the aperture once more.
Flaws to expect on a lower tier copy
- Day and night wheel dressed as a moon phase, giving a full cycle in 24 hours.
- Moon aperture set off center, so the disc clips the dial edge.
- Date window that lags several hours behind the day change.
- Corrector plungers that sit too deep in the case and need a pin tool to reach.
- Solar and lunar discs printed with a flat gray instead of a blued or silvered finish.
Legality and resale
A replica carries no brand warranty and cannot be sold as an original. Reselling one as genuine is counterfeiting in most jurisdictions. Treat the price as you would any fashion purchase and assume there is no resale market.