The most dependable check on a fake Blancpain moon phase is the moon disc behind the aperture. On a real Villeret Quantième Complet, that disc is a finished part driven by a 135 tooth wheel through a 29.5 day cycle, and Blancpain states the mechanism needs correction once every 122 years and 46 days. Copies use a printed disc, a flat crystal, or a moon display slaved to the date wheel, so the moon sits off center or jumps at midnight with the date. That check removes a large share of what circulates. The criteria below cover the rest: moon disc, dial print, case and crown, movement, caseback markings, and paperwork.
1. The Moon Phase Aperture and Disc
Ask for a macro photo of the aperture with the moon at a partial phase. On a genuine piece the moon has a modeled profile, the stars on the disc are sharp, and the aperture edges are cut clean with no bleeding onto the dial. On copies the moon is a flat print, the star field is blurry, and the disc edge often shows a visible gap or a plastic sheen.
- Pros: Visible in photos, needs no tools, and the disc is a separate manufactured part that is costly to reproduce with any fidelity.
- Cons: Photo etched replica discs now look convincing at arm's length, and dim listing photos hide the difference. The check can confirm a problem but cannot confirm a watch is real.
Use it when: you are screening an online listing and need a fast first filter before you spend money on an inspection.
2. Dial Printing, Markers, and Hands
Pad printing on a genuine dial holds tight edges. The signature is thin and even, the calendar numerals sit in correct alignment inside their windows, and applied markers show polished bevels that catch light from two directions. Replica dials show thicker ink, uneven numeral spacing, and markers that appear flat under the same lighting.
- Pros: Cheap to evaluate if the seller will send a 10x close up of the signature, the numerals, and the Swiss Made line.
- Cons: Phone cameras flatten texture and add glare. A strong fake photographed well can pass this stage.
Use it when: you already have a movement photo or an inspection booked, and you want a second data point.
3. Case, Crown, and Proportions
Current 6654 references use a round case with a stepped profile and a defined lug curve. Copies often get the diameter close and the thickness wrong, which changes how the watch sits on the wrist and how the lugs meet the strap. The crown is a useful tell: genuine crowns show fine knurling and a crisp logo, while copies show shallow teeth and a soft stamp.
- Pros: Thickness and lug shape are measurable, so you can compare numbers instead of opinions.
- Cons: Case work is the easiest part of a counterfeit to copy well, so this check has the lowest signal on its own.
Use it when: you can handle the watch in person with calipers.
4. The Movement Through the Caseback
This is the strongest single test. A genuine complete calendar caliber shows a full module with day, date, month, and moon phase, Geneva stripes on the bridges, and a gold rotor with engraved branding. Correctors for the calendar functions sit recessed into the case band. Copies generally show a base movement with a bolted on module, mismatched finishing, and correctors that either do not exist or sit proud of the case.
- Pros: Finishing and module architecture are hard to fake at a price that still leaves a profit.
- Cons: Some sellers post stock movement photos that belong to another watch.
Use it when: the deal is large enough to justify a watchmaker opening the case.
5. Caseback Engraving, Reference, and Serial
Genuine engraving is crisp and consistent in depth, and the reference number matches the dial configuration. Serial records are not public, so no online lookup settles the question. Blancpain or an authorized service center can confirm a serial and a reference against their records.
- Pros: A service estimate gives you paperwork and a professional opinion you can rely on.
- Cons: Engraving is simple to reproduce, so a clean caseback proves little by itself.
Use it when: you are paying a meaningful sum and can wait for an official answer.
6. Box, Papers, and the Seller Story
Full sets exist, and counterfeit sets exist in equal volume. A box, a card, and a receipt do not authenticate a watch. Treat the story as the weakest evidence in the file and weight the physical checks above it.
- Pros: Complete sets are easier to resell and to service.
- Cons: Paperwork is the cheapest thing to fake, and genuine watches sometimes arrive with fake documents.
Use it when: you are comparing two otherwise equal watches and need a tiebreaker.
7. Shopping the Copy Market: What You Are Actually Buying
If you are considering a first copy because the look matters more than the mechanism, go in with clear expectations. Most copies at accessible prices use a printed moon disc or a 24 hour day and night disc disguised as a moon phase, so the function is decorative. Water resistance is a claim rather than a tested rating, spare parts are unavailable, and no service center will touch the watch. In the United States, trafficking in counterfeit goods is prohibited and Customs can seize counterfeit imports, so a cross border order carries real risk.
- Pros: Low entry cost, and the silhouette reads as a dress watch from a distance.
- Cons: No service path, no parts, near zero resale, legal exposure on import, and a moon phase that may not track the lunar cycle at all.
Use it when: you want a costume piece and accept that it is a disposable object, not a watch you maintain.
Pre-Purchase Checklist
- Request a macro photo of the moon aperture at a partial phase.
- Request a 10x close up of the dial signature and calendar numerals.
- Request a clear, well lit caseback photo with the movement visible.
- Compare case thickness and lug shape against the reference specification.
- Send the serial and reference to Blancpain or an authorized service center.
- Budget for an independent watchmaker inspection before funds change hands.