A counterfeit Audemars Piguet Royal Oak Offshore reference 25721 gives itself away in four places: case thickness, dial texture, caseback engraving, and the movement under the back. The 25721 is the 1993 original, a 42 mm chronograph built in limited annual batches with an integrated bracelet and a modular chronograph calibre. Replica makers copy the silhouette. They rarely copy the details you can measure. Work through the checks below in order and a genuine Offshore separates from a replica in about twenty minutes.
What you need before you start
- Digital calipers that read to 0.1 mm
- A 10x jeweler's loupe
- A bright, angled light source
- Reference photos of a documented 25721 dial and caseback
- Access to Audemars Piguet service records or an Extract from the Archives
- A watchmaker willing to open the caseback
Step-by-step authentication checks
- Measure the case with calipers at the widest point of the bezel, crown excluded. A genuine 25721 measures 42 mm across and roughly 15 mm thick. Replicas commonly run 43 to 44 mm wide, or sit 1 to 2 mm thin because the builder used a slim donor movement and a shallower caseback.
- Put the dial under the 10x loupe and study the Mega Tapisserie grid. Genuine squares have sharp, raised edges with a brushed top and straight side walls. Fake grids look stamped, rounded, or painted, and the squares vary in size across the dial.
- Compare the subdial layout and hand lengths to reference photos. The 25721 runs running seconds at 12, a 12-hour counter at 6, and a 30-minute counter at 9. Check that each hand reaches its track and that the date window sits level with the 3 o'clock marker.
- Examine the caseback engraving under raking light. Genuine text is cut deep with crisp inner edges, even spacing, and a consistent font. Laser-etched replica text looks shallow, fuzzy, or double-lined at the edges.
- Read the reference and serial numbers, then cross-check them against Audemars Piguet records. A 25721 caseback should carry a reference beginning 25721ST for the steel version, followed by the case and bracelet codes. Numbers that do not match any service record, or that repeat across listings, point to a fake.
- Inspect the bracelet and clasp. Genuine links taper with a polished bevel that follows the case lines, the end links sit flush against the lugs with no gap, and the clasp engraving matches the caseback font.
- Have a watchmaker remove the caseback and inspect the movement. Early 25721 examples use calibre 2226/2840, later ones 2326/2840, both modular chronographs on a Jaeger-LeCoultre base. Look for Geneva stripes, perlage on the plates, polished screw heads, and an engraved rotor carrying the AP mark and the calibre number.
- Operate the chronograph and crown. Push each pusher and confirm a firm, short travel with a clean start, stop, and reset to zero. Screw the crown down and feel for clean threads. Gritty travel or a pusher that sinks without resistance means the case holds a cheap third-party module.
Red flags that end the inspection
- A dial grid with soft or painted edges
- Engraving that washes out under the loupe
- A rotor with a printed or stickered logo instead of engraved metal
- A movement with no calibre number stamped or engraved on the rotor or bridges
- A seller who refuses to let a watchmaker open the case
- A price far below the current market range for a documented 25721
Where to verify
Send the reference and serial to an Audemars Piguet boutique or authorized service center and request an Extract from the Archives. That document confirms the production date and the configuration the watch left the factory with. Pair it with a written opinion from an independent watchmaker who has serviced Royal Oak Offshore references. Paperwork plus a movement inspection is the only combination that settles authenticity.