Short answer
A replica Audemars Piguet Royal Oak Extra Thin is a copy of the Royal Oak Jumbo, the 39 mm extra-thin reference people usually mean by that name. The genuine current model, reference 16202, is 8.1 mm thick and runs the in-house calibre 7121. Most copies in circulation are 9 to 10.5 mm thick and use a generic third-party automatic movement with a decorative rotor. That thickness gap is the most reliable giveaway in hand. One more thing up front: trafficking in counterfeit watches is a federal crime in the United States, and shipments get seized at the border on a routine basis.
The real watch the copies target
The Royal Oak landed in 1972, designed by Gerald Genta, and the thin 39 mm steel version earned the Jumbo nickname from collectors. The lineage runs from the original 5402 through the 15202 to today's 16202. What defines the family is the case height and the integrated bracelet, not the dial color or the tapisserie pattern. AP calls the line Extra-Thin because the whole point is a mechanical watch with a date that slides under a shirt cuff. Copy makers chase that silhouette because it is instantly recognizable and expensive to do properly.
Thickness is where copies give themselves away
Getting an automatic movement, a dial, a date wheel, and a sapphire back into an 8 mm case takes real engineering, and the 7121 is a thin movement built for that job. Replica factories work with movements that are far easier to source, so they build the case around the movement instead of the other way around. I measure first. Calipers on the caseback, not the crystal. A spec sheet claiming 8.1 mm and a watch that reads 10 mm tells you what you need to know.
Movements inside the copies
- Miyota 9015 based automatics, often with an engraved or skeletonized rotor meant to suggest an AP calibre
- Chinese automatic movements with added plates and fake jewel settings
- Rotor engraving that copies AP lettering but not the actual architecture underneath
None of these are bad movements in isolation. They are simply not the movement the case was designed around, and that shows in the date position, the winding feel, and the beat rate.
Case, bracelet, and finishing
The Royal Oak bracelet is the hard part. Genuine links taper and articulate with a specific drape, and the bevels on the case edges catch light in a way that hand polishing rarely reproduces. On copies I look at the chamfer along the bezel screws, the flatness of the brushed top surfaces, and whether the screws sit in a straight line. Small misalignments stack up fast.
What "first copy" actually means
First copy is a seller term, not a quality standard. There is no grading body, no factory registry, and no consistent spec behind the label. Two watches sold under the same phrase can come from different workshops with different cases. Treat the wording as marketing and judge the object.
The legal side in the US
Selling or distributing counterfeit trademarked goods is illegal under 18 U.S.C. 2320, and importing them is barred by 19 U.S.C. 1526. US Customs and Border Protection seizes counterfeit watches regularly, including shipments sent by mail to individuals, and the buyer typically loses the money and the watch. There is also no warranty, no service path, and no legitimate resale channel.
What I check first, in order
- Case thickness with calipers
- Date window position and font
- Bracelet taper and link articulation
- Bezel screw alignment and slot depth
- Movement finish visible through the caseback