A skeleton watch has its dial, movement bridges, and mainplate cut away, so the wearer can see the wheel train, escapement, and balance wheel running in real time. The French call it montre squelette. The technique dates to 18th-century French pocket-watch workshops, where metal removal was done by hand with saw, file, and engraving burin. The entire movement had to be re-engineered so that removing material did not compromise structural rigidity, because a skeletonised bridge is far weaker than a solid one.
The skeleton wristwatch emerged in the 1930s when Cartier, Patek Philippe, and Audemars Piguet produced limited-run skeletonised pieces. The mainstream wristwatch revival came in the 1970s Geneva, part of the broader haute-horlogerie comeback that also produced the Royal Oak. AP's skeleton Royal Oak Ref. 5829 (1979) and Vacheron Constantin's Squelette pieces established the modern skeleton aesthetic: elaborately decorated bridges and mainplate, engraved by hand, visible from both dial and caseback.
The hand-skeletonised process is mechanical sculpture. A skilled watchmaker takes a solid bridge, marks the material to be removed, drills starter holes at interior corners, cuts with a jeweller's saw, files to final shape, then engraves the remaining surfaces with decorative patterns. 200 hours of bench work per movement is typical at haute-horlogerie standard. Every removed element must still leave a structurally stiff, kinematically sound assembly. Engraving that follows the cutout is a signature of the best work.
Modern CNC-skeletonised movements produce visually similar results at a fraction of the cost. The Royal Oak "Openworked" Perpetual Calendar and skeleton Tourbillon, Hublot Spirit of Big Bang Meca-10, Richard Mille RM 11 Flyback Chronograph, and most modern tourbillon watches use CNC-cut bridges. A purist can distinguish hand-skeletonised work by the presence of hand-engraving and by the sharpness of interior angles; CNC bridges show uniform rounded fillets at every interior corner.
