What Is a Skeleton Watch? How the Hartley Legacy Shows Its Heart

In short: a skeleton watch is a mechanical watch with its dial and movement plates cut away so you can see the gears, springs and jewels working inside. It keeps time exactly like any other mechanical watch. The difference is that the engine is on display rather than hidden behind a solid face.

Most watches hide the most interesting part. Behind a solid dial sits a movement full of gears, springs and tiny synthetic rubies that nobody ever sees. A skeleton watch turns that idea inside out. It removes as much material as possible so the movement becomes the dial, and the watch becomes something you can look into rather than just look at.

How a skeleton watch works

Underneath, a skeleton watch is still a normal mechanical watch. It has a mainspring that stores energy, a gear train that carries that energy to the hands, an escapement that releases it in tiny controlled steps, and a balance wheel that swings back and forth at a steady rate to keep time.

What changes is the way the parts are made. The plates and bridges that hold the movement together are normally solid pieces of metal. In a skeleton movement they are opened up, cut back to the minimum structure needed to stay strong and keep every wheel in its exact position. The dial is either removed completely or reduced to a ring that carries the hour markers.

Look through the crystal of a skeleton watch and you are watching the mechanism actually run: the balance wheel ticking several times every second, the gears turning at different speeds, and the jewels that the moving parts sit on.

Skeleton vs open heart vs exhibition caseback

These three terms often get mixed up, so here is the difference.

• Open heart: a small window in an otherwise solid dial, usually showing just the balance wheel.
• Exhibition caseback: a clear sapphire back so you can see the movement from behind, while the front dial stays solid.
• Skeleton: the dial and the movement itself are opened up so you can see through the watch from the front, and often from the back as well.

The Hartley Legacy is a skeleton watch with an exhibition caseback, so you see the movement from both sides. Turn it over and you can watch the rotor spin as it winds the mainspring.

What are the jewels for?

The jewels in a mechanical watch are small synthetic sapphires or rubies used as bearings. A steel pivot turning against metal would wear quickly and add friction. Setting the pivots in jewels, which are extremely hard and polished very smooth, reduces that friction and wear dramatically. That is a big part of why a well looked after mechanical movement can run for decades.

The Legacy uses a Miyota automatic movement with 21 jewels. Because the movement is skeletonised you can actually see them, including the hints of purple that catch the light when you tilt your wrist.

Why most skeleton watches are automatic

You could skeletonise a quartz watch, but there would not be much to look at: a battery, a circuit board and a small stepping motor. Skeleton watches are almost always mechanical because a mechanical movement is a genuinely beautiful thing to watch.

The Legacy is an automatic, which means it winds itself. A weighted rotor spins as your wrist moves and tightens the mainspring, so as long as you wear it, it keeps running. A full wind gives roughly 40 hours of power reserve, enough to sit on your bedside table overnight and still be ticking in the morning. Read more about the difference in our guide to automatic or quartz watches.

What to look for when buying a skeleton watch

A slim, comfortable case

Skeleton movements look best in a case that does not feel bulky on the wrist. The Legacy is 43mm wide but only 11mm thick, the thinnest we could achieve around a mechanical movement, so it sits close to the wrist and slides under a shirt cuff.

Sapphire crystal on both sides

If the movement is the show, the glass is the window. Mineral glass scratches easily and quickly clouds the view. Sapphire crystal is second only to diamond in hardness. The Legacy uses sapphire on the front and back, with anti reflective coating on both sides of the front crystal so you see the movement rather than your own reflection.

Legibility

A busy skeleton dial can be hard to read at a glance. Look for strong, contrasting hands and clear hour markers. The Legacy uses bold Roman numerals on a dark chapter ring around the open centre, so it is still easy to tell the time.

Everyday water resistance

Some skeleton watches are delicate dress pieces with very little water resistance. 50 metres is a practical minimum for something you will wear every day, and it is what the Legacy is rated to.

Quality case material

316L stainless steel resists corrosion from sweat and salt, does not tarnish and is gentle on skin. It is the same grade used in surgical instruments and quality watch cases.

How to look after a skeleton watch

A skeleton watch needs the same care as any automatic. Wear it regularly or give the crown a few turns to keep it running, keep it away from strong magnets, push the crown fully in around water, and have it serviced every few years. We cover all of this in detail in how to look after an automatic watch.

Why we built the Legacy as a skeleton

Hartley started in 2014 with minimalist quartz watches, and our Heritage has since sold more than 10,000 pieces in over 50 countries. The Legacy was our chance to make something more ambitious: a mechanical watch you can look into, made in numbered editions of just 125 per colour, with your edition number engraved on the case.

Skeletonising the movement felt right for a watch designed to be kept and handed down, because it shows exactly what you are holding. There is nothing hidden, and nothing to hide.

Frequently asked questions

Are skeleton watches less durable?

Not meaningfully, if the movement is well designed. The plates are cut back but the structure that holds each wheel in place remains. Treat it like any automatic: avoid hard knocks and have it serviced every few years.

Are skeleton watches hard to read?

Some are. Choose one with contrasting hands and a clear chapter ring for the hour markers, as on the Legacy.

Do skeleton watches need a battery?

Almost all skeleton watches are mechanical, so no. An automatic skeleton like the Legacy is powered by the movement of your wrist.

Is a skeleton watch suitable for every day?

Yes, provided it has sapphire crystal and a sensible water resistance. The Legacy is rated to 50 metres and built for daily wear.

Explore the Legacy collection in gold, silver, black and rose gold, each limited to 125 numbered pieces.