A Skeleton Movement is the openworked style in which the dial and the bridge surfaces are cut away so the wheels, balance and mainspring become visible to the eye. The idea goes back to around 1760 and the French watchmaker André-Charles Caron, born in 1698 and watchmaker to Louis XV, who worked out a subtractive method: stripping every non-load-bearing piece of metal from the plates and bridges without compromising the movement's structural integrity. There is a distinction worth knowing in the trade. A skeletonised movement has material removed from an existing calibre after the fact, while an openworked movement is engineered to be open from the design stage. In both cases, what you are looking at is the mechanism itself, not decoration applied on top of it.
The field today runs across every price tier. The Cartier Santos-Dumont Skeleton uses the calibre 9629 MC with a micro-rotor shaped like Santos-Dumont's Demoiselle aircraft, and it retails around £27,000, with the larger 43.5mm WHSA0044 from 2025 a touch above that. Higher up sits the Audemars Piguet Royal Oak Double Balance Wheel Openworked: the 41mm steel reference 15407ST, built on calibre 3132, lists near £61,000 retail but trades well past £120,000 used, while the yellow gold 15407BA is around £81,000. Higher still, the titanium Royal Oak Perpetual Calendar Openworked sits near £185,000. Over at Zenith, the Defy Skyline Chronograph Skeleton carries an openworked El Primero 3600 near £12,400, while the time-only Defy Skyline Skeleton runs about £8,000. The Roger Dubuis Excalibur Automatic Skeleton, finished to Geneva Seal standards, starts near £48,000 in titanium.
The first thing to judge is the quality of the finishing. The difference between a bridge whose edges are hand-bevelled and polished, with clean sharp internal angles, and one simply hollowed out by CNC with dull edges, is visible at arm's length and it drives the price. The second issue is legibility. An open dial lets light through from every direction, so hand contrast is the weak link on most skeletons; look at the watch over different backgrounds in person before you commit. This style suits the buyer who wants to wear the mechanics as jewellery and does not mind being noticed; if you want a quiet, classic daily watch, it can be tiring.
Do not write off the entry level. The Hamilton Jazzmaster Skeleton, running an 80-hour calibre based on the ETA C07.111, offers honest openworking at roughly £1,100 to £1,200, and the Tissot Chemin des Tourelles Squelette opens a similar door in steel and gold PVD at dress-watch proportions. At the Hublot end, the Big Bang and Square Bang Unico Sapphire put the HUB1280 Unico flyback chronograph on show with an exposed column wheel and date ring, a louder and more modern reading of the same idea. Skeleton, in other words, names an approach rather than a single price bracket.