Identify an Audemars Piguet: Reference and Model Guide

Audemars Piguet engraves the identifying numbers on the caseback rather than between the lugs.

• Caseback ring. On modern Royal Oaks with a sapphire display back, the short reference such as 15500ST and the individual case number are engraved on the metal ring around the crystal. The case number is usually a letter followed by digits.
• Solid caseback. Older Royal Oaks and many Jules Audemars and Millenary models have solid backs with the engraving on the outside, often together with the Royal Oak name and a number.
• Movement. The calibre carries its own number, visible through a display back or when the watch is opened.
• Papers. The warranty card or certificate shows the full reference, for example 15500ST.OO.1220ST.01, along with the case and movement numbers.

The dial does not show the reference. The AP monogram and the Audemars Piguet signature appear on every model, so they identify the brand but not the watch. For a general explanation of how brands build their codes, see watch reference numbers explained.

A full reference such as 15500ST.OO.1220ST.01 breaks into four parts separated by dots.

Part	Example	Meaning
Model and case material	15500ST	15500 is the model, ST the case material. 15xxx are Royal Oak time and date models, 26xxx chronographs and complications including the Offshore, 77xxx smaller Royal Oaks
Gem setting	OO	OO is no gem setting; ZZ is diamond-set
Bracelet or strap and its material	1220ST	1220ST is the steel bracelet of the 41 mm Royal Oak, 1240ST the Jumbo bracelet, 1320ST that of the 15510. Codes beginning with A are straps: CA rubber, CR leather
Dial variant	01	Dial colour or variant; numbering is specific to each model

Material codes: ST steel, OR pink gold, BA yellow gold, BC white gold, PT platinum, TI titanium, CE ceramic, with combinations such as IP for titanium and platinum. Sellers usually quote only the first part, such as 15202ST, because model and material identify the watch in most conversations; the bracelet and dial codes matter when two watches share a model number but differ in dial colour or strap.

Audemars Piguet does not publish serial-to-year tables. Case numbers follow letter series, and collectors use the letter as a rough indicator of period, but the mapping is approximate and unofficial.

• Vintage Royal Oak. The earliest 5402ST Jumbos carry A-series numbers, followed by B, C and D series; the letter and number are central to how a vintage Jumbo is described and valued.
• Modern watches. The warranty card date is the reliable indicator. Production usually precedes the sale by months rather than years.
• Reference generation. The model number gives a window. The 15400 ran from 2012 to 2019, the 15500 from 2019 to 2022, and the 15510 from 2022. The 15202 Jumbo was discontinued at the end of 2021 and replaced by the 16202.

Audemars Piguet's Heritage department can research a watch from its case and movement numbers. For a vintage purchase, that record and a dated service history are worth more than any online chart, and the case number on the watch must match the papers.

• Royal Oak Jumbo (15202, 16202): 39 mm, very thin, Petite Tapisserie dial, no seconds hand, date at 3, logo at 6 and brand name at 12.
• Royal Oak 41 mm (15400, 15500, 15510): Grande Tapisserie dial, central seconds, date at 3. Logo at 12 on the 15400 and 15500, at 6 on the 15510. The 15500 has longer markers and a date window at the dial edge compared with the 15400.
• Royal Oak 34 and 37 mm (77350, 15450): the same design in smaller cases, with diamond bezels on ZZ versions.
• Royal Oak Chronograph (26331): 41 mm with three subdials on a Grande Tapisserie dial and rectangular pushers.
• Royal Oak Offshore (26470, 26238): 42 mm or larger, thicker, rubber or ceramic crown and pushers, Mega Tapisserie dial with larger squares.
• Royal Oak Concept: openworked, futuristic cases with exposed mechanics.
• Code 11.59: round bezel on an octagonal middle case, double-curved crystal, launched 2019.
• Millenary: oval case with an off-centre dial.
• Jules Audemars: classic round dress watches.

• 15400 vs 15500 vs 15510. All are 41 mm. Logo at 12 with the date set in from the edge is the 15400; logo at 12 with the date at the edge and longer markers is the 15500; logo at 6 is the 15510.
• 15202 vs 16202. Both are 39 mm Jumbos and nearly identical from the front; the 16202, introduced in 2022, has a new calibre visible through the caseback.
• Royal Oak vs Royal Oak Offshore. The Offshore is bulkier, with rubber or ceramic crown and pushers and a larger dial pattern.
• Royal Oak vs Nautilus. Both are Gerald Genta designs. The Royal Oak has a sharp octagon with eight screws; the Nautilus bezel is rounded, screwless, with ears on the case. See our Patek Philippe identification page.
• Integrated-bracelet homages. Affordable watches borrow the octagonal bezel. Eight hexagonal screws, a tapisserie dial and the AP monogram together separate a Royal Oak.

The Royal Oak is heavily counterfeited, so treat a visual match as a hypothesis; see our guide on how to spot a fake luxury watch.

Royal Oak references differ in details that a good photo captures and a poor one hides.

1. Shoot the dial straight on in diffuse light so the tapisserie pattern is visible; flash flattens it, and pattern size is a main cue.
2. Keep the bezel and first bracelet links in frame; their finish and taper point to the generation.
3. Add a caseback photo if you can; the engraved reference often settles it outright.

WatchID compares the image against a reference database and returns ranked candidates with model names and references. For a blue-dial steel 41 mm Royal Oak it will typically show the 15500ST and 15400ST together, and sometimes the 15510ST, because they share case and bracelet and differ in dial details; logo position and date placement let you choose.

The result is an identification, not a judgement of authenticity. Confirm the reference against the caseback and warranty card, and read how to identify a watch from a photo for the general method. If the watch is not an AP at all, our Rolex identification page covers the usual alternative.