The short answer
Most watches sold as a "fake Audemars Piguet Royal Oak Offshore 26420" are not one product. They are several different builds sharing a reference number. The better ones come out of the same Guangdong workshops that make top-tier Rolex copies, run a modified ETA 7750 or a Chinese clone of it, and sell for $400 to $900. The worse ones are $120 mall-tier pieces with a glued bezel and a printed dial. Both show up under the same search term, and the gap between those two tiers is wider than the gap between the mid tier and the genuine watch.
What the genuine 26420 actually is
AP launched the 42mm Offshore chronograph in 2021 as the replacement for the older 44mm generation. It carries the in-house Calibre 4404: an integrated flyback chronograph with a column wheel and vertical clutch, roughly 70 hours of reserve, and a sapphire display back so you can see it. The case is 42mm across on a steel, titanium, or ceramic build, with the octagonal bezel and eight hex screws that define the line, a Mega Tapisserie dial, and sapphire on both sides.
Pricing on the secondary market runs somewhere between roughly $35,000 and $60,000 depending on material and condition. Keep that number in your head while you read the rest.
Where the replicas fall apart
Movement, and the thickness it forces
By coincidence, the 7750 subdial layout matches the Offshore's: running seconds at 9, 30-minute counter at 12, 12-hour counter at 6. That is why replica makers gravitate to it. The problem is everything else. The 7750 stack is thicker, so a fake 26420 typically sits 1 to 2mm taller than the real watch, and that extra height is visible in profile from across a table.
The flyback is the giveaway. On a genuine 4404 you can press reset while the chrono is running and it snaps back to zero and keeps going. On a 7750-based fake you have to stop, then reset. Try it. The pushers also feel mushy instead of crisp, the rotor winds with a gritty rasp, and the date changes with a slow crawl instead of a snap.
Case and finishing
AP's case work is the hard part to copy. The genuine watch has sharp, deliberate transitions between brushed and polished surfaces, and the lug chamfers stay crisp under a fingernail. Replicas usually over-polish, which softens those edges into something rounded. Run your thumb along the lug tops. If it feels like a river stone, that is not AP finishing.
Dial texture
The Mega Tapisserie squares should be uniform in depth with walls sharp enough to throw a clean shadow. Tilt the watch under a lamp and watch the pattern move. On fakes the squares are shallow and slightly wavy, and the grid is sometimes shifted off-center relative to the date window. Dial print is another shortcut: the logo weight and letter spacing drift, and the date font rarely matches.
Bezel screws and caseback
Eight hex screws, tight, sitting flush, with clean slots and no glue residue or tool marks around them. Misaligned or proud screw heads are common on fakes. Flip it over, and the 26420 should have a sapphire display back showing a decorated movement. If a seller shows you a "26420" with a solid caseback, the watch is wrong before you even look at the movement. On the real thing, the caseback engraving is deep and the serial fonts are consistent.
What the replica tiers cost
- $100 to $250: printed dial, glued bezel, quartz or cheap automatic, wrong case proportions.
- $350 to $650: the common mid tier. Decent dial texture, 7750 base, wrong thickness, no flyback.
- $700 to $1,200: the best available. Better case finishing, sharper dial, still no flyback and still thicker than real.
None of them hold value. A $900 fake is about 2% of the price of the watch it copies, and it will not survive a service interval the way the real movement will.
A quick check in the hand
- Measure the thickness. Extra height is the first tell.
- Test the flyback while the chrono runs.
- Look at the eight bezel screw slots for alignment and glue.
- Tilt the dial under raking light and check the Tapisserie depth.
- Confirm the sapphire caseback and look at the movement finishing.
- Feel the pushers and the crown threads.
- Watch how the date flips and check the date font.
The honest bottom line
If you want a watch that reads as an Offshore from three feet, the mid tier does that job. If you want the actual 26420, buy the real one. And if you are shopping used, treat this reference as one of the most-faked watches on the market, price a service and an authentication into the deal, and walk away from any seller who gets vague about the movement or the caseback.