The most reliable test for anything sold as an Audemars Piguet perpetual calendar, including listings tagged with the code 3399, is movement and caseback verification by Audemars Piguet service or a qualified watchmaker. Dial print, bracelet finishing, box and paperwork only support that test. This guide judges four things in order of weight: caliber and movement architecture, case and bracelet finishing, dial and calendar printing, and the documentation chain. It does not recommend buying counterfeits, because the legal and financial exposure lands on the buyer.
What the code 3399 usually means
In practice, 3399 shows up as a marketplace, auction platform, or seller SKU, not as an official Audemars Piguet reference. Genuine perpetual calendar watches from the brand carry the manufacturer's own reference format and a stated caliber number. Sellers who cannot explain where the number comes from, or who mix it with unrelated reference numbers in the same listing, are describing inventory codes rather than watches.
- Ask for the reference engraved on the caseback and the caliber on the movement bridge, as photographs.
- Compare both numbers against documentation from Audemars Piguet or a service center.
- Treat any refusal to photograph the movement as a stop signal.
Criterion 1: Movement and caliber
A perpetual calendar is one of the hardest complications to copy. Thin automatic bases with added calendar modules produce specific visual signatures: module thickness, date and moonphase placement, and the finish of bridges, jewels, and screws. Counterfeits typically rely on a generic movement with decorative plates glued or screwed over it.
Green flags
- Movement photographs show hand finishing, Geneva stripes, jeweled pivots, and engraved caliber markings.
- Crown position changes the day, date, month, and moonphase correctly, one step at a time.
- A watchmaker can identify the caliber in person without removing decorative cover plates.
Red flags
- Blurry movement photos, or none at all.
- Calendar indications that jump together or cannot be corrected independently.
- Caseback depth that suggests a thick modular stack rather than a slim perpetual calendar build.
Criterion 2: Case and bracelet finishing
Audemars Piguet case work depends on alternating brushed and polished surfaces with crisp, sharp transitions, plus tight bracelet tolerances and screws that align. Replicas tend to round off those edges, leaving soft bevels and uneven brushing that you can see in raking light.
Green flags
- Bevels stay sharp under a loupe and brush lines run in one direction per surface.
- Bracelet links flex without rattling and screw heads sit flush.
- Weight and balance feel consistent with a precious metal or steel case of that size.
Red flags
- Polished edges bleeding into brushed areas.
- Loose end links, stripped screws, or a bracelet that tapers unevenly.
- Plating that shows a different color where the case rubs against a desk or clasp.
Criterion 3: Dial, hands, and calendar printing
Print quality is where most counterfeits give themselves away at arm's length. Genuine dials hold sharp edges on applied markers, even lume or paint fill, and text with consistent stroke width. Calendar subdials should sit on the correct axis and line up with their apertures.
- Check that month, day, date, and moonphase windows are centered and cut cleanly.
- Look for typography that thickens or fades at the ends of words.
- Confirm hand finishing matches the dial finish instead of looking flat or over-polished.
Criterion 4: Papers, service history, and provenance
Documentation is the cheapest check and the easiest to verify. A genuine perpetual calendar usually comes with a matching serial on the case, warranty card or extract, and a service trail. Counterfeit packages copy the format but rarely keep serials consistent across card, case, and movement.
- Match the serial in three places: paperwork, caseback, and movement.
- Request service receipts and confirm them with the listed service center.
- Buy only through channels that allow a third-party inspection period with a full refund.
Recommendation by use case
If you want the perpetual calendar look and function, buy a genuine pre-owned Audemars Piguet with service records, or choose a watch from a brand that designs its own perpetual calendar. You get real calendar accuracy, resale value, and service support. If you already own a watch sold as a 3399 piece and want certainty, book an inspection with Audemars Piguet service or a qualified independent watchmaker before spending on repairs. Counterfeit watches are subject to seizure at import, and the money you save at purchase rarely survives a single service attempt.