Short answer
Audemars Piguet does not make a Royal Oak with reference 4101. Royal Oak case references carry five digits and start with 5, 1, 2, or 26: 5402, 14790, 15202, 15400, 15500, 16202, 26240. A listing that says Royal Oak 4101 uses a number that matches no AP case reference. Most of these listings are counterfeits, seller codes, or typos for a movement number.
Where the number 4101 comes from
Four-digit numbers at Audemars Piguet sit on movements, not cases. AP calibre families include 2120, 2385, 3120, 4302, and 4401. Case references run five digits. When a seller writes ref 4101, ask for the engraving on the caseback and a photo of the movement. A real Royal Oak carries the reference number, the case number, and the model name engraved on the back. A seller who cannot send that photo is not selling a Royal Oak.
Checks that work on any Royal Oak
- Caseback: reference and case numbers are engraved, not laser printed. Edges are crisp under a loupe.
- Dial: the tapisserie grid is raised and sharp. Print is thin. The date sits centered at 3 o'clock and uses the same font as the hour markers.
- Movement: the rotor holds a skeletonized AP logo and Geneva stripes. Rate is 21,600 or 28,800 vibrations per hour.
- Bracelet: links taper from case to clasp. Screws sit flush. End links meet the case with no gap.
- Case size: the Royal Oak Jumbo 15202ST measures 39 mm wide and 8.1 mm thick. The 15400 and 15500 measure 41 mm.
- Hands and markers: applied gold markers with polished bevels. Fake dials show flat paint and soft edges.
Price signals
A steel Royal Oak Jumbo sells for five figures in US dollars on the secondary market. A new Royal Oak 4101 priced at $300 to $900 is a counterfeit. A genuine watch at that price does not exist.
Legal note for US buyers
Counterfeit watches are illegal to import into the United States. US Customs and Border Protection can seize a shipment and destroy it. A replica also fails at every service center and dealer, so resale and repair are closed to you.
What to ask a seller
- Photo of the caseback engraving.
- Photo of the movement with the rotor visible.
- Reference number and case number, written out.
- Service history and original papers.
If any of those four items is missing, stop. The reference 4101 does not exist in the AP catalog, and no paperwork will change that.