Short answer: The Audemars Piguet Royal Oak Offshore Chronograph reference 25940 is a 42 mm steel chronograph from the Offshore line that Audemars Piguet launched in 1993. Copies of this reference exist, but they are less common than fake Rolex models. Most copies put an Asian Valjoux 7750 clone inside a third-party case. The dial surface, the caseback engraving, and the movement finish are where copies fail inspection.
What the reference 25940 is
The Royal Oak Offshore arrived in 1993 as reference 25721ST, a 42 mm steel chronograph designed by Emmanuel Gueit and nicknamed "The Beast" by collectors. The 25940 sits in the Offshore chronograph line that followed, with the wide bezel, the eight hexagonal bezel screws, a rubber-clad crown and pushers, and a dial with the Mega Tapisserie grid.
Offshore chronographs of that period ran an Audemars Piguet calibre built on a Frederic Piguet 1185 base. Bridges and the rotor carry Geneva stripes, perlage, and engraved AP markings. Subdials sit at 12, 6, and 9 o'clock. Case metal, dial color, and strap change by variant, so confirm the exact configuration against Audemars Piguet records rather than against a photo.
How replicas of the 25940 are built
- Movement. An Asian Valjoux 7750 clone, a cam-actuated chronograph that beats at 28,800 vph. It shares the 12-6-9 subdial layout with the genuine calibre, so the dial side looks close in photos. Rotor engraving, screw heads, and perlage differ under a loupe.
- Case. Copied from a scan of a genuine case. Many copies measure 1 mm to 2 mm thicker than the original, and case middle thickness is the first number to check with calipers.
- Dial. The genuine Mega Tapisserie grid is molded, with raised squares and sharp edges. Copies show shallow squares with rounded edges and printed text with a soft edge under magnification.
- Caseback. Reference and case numbers are laser engraved. Copies use shallow cuts, wrong font weight, and mismatched number spacing.
- Crystal and bezel screws. Aftermarket sapphire, uneven slot depth on the eight bezel screws, and hex slots that do not line up with the caseback pattern.
Checks before buying or trading
- Open the caseback with a watchmaker and inspect the movement. Genuine AP finishing, engraving, and rotor text do not appear on a 7750 clone.
- Compare the reference and case numbers against any papers, and ask for service records.
- Weigh the watch and measure the case with calipers. Note thickness at the case middle.
- Check the price against the used market. A 25940 in steel with papers sells in the thousands to tens of thousands of US dollars, based on metal and condition. A price far below market is a warning.
- Send the watch to Audemars Piguet for service. The brand will not service a counterfeit and returns it unserviced.
Legal position in the United States
18 U.S.C. 2320 makes trafficking in counterfeit goods a federal crime. A first offense carries up to 10 years in prison and a $2 million fine for an individual. U.S. Customs and Border Protection can seize and destroy counterfeit watches at the border, and a seller who passes a copy off as genuine faces civil claims under the Lanham Act.
Numbers and specifications change by variant and by production year. Facts that cannot be confirmed from Audemars Piguet records, or from the physical watch in hand, should be treated as unverified.