Be Careful!

Watchmaking takes an incredibly careful touch. Whether you're using tweezers, files or other tools, the mantra is "firm, careful and controlled." Unfortunately for this jewel, I was a little too rough.

Jewels are a critically important part of a watch movement. They locate a watch's various wheels, and provide a stable, durable, low-friction place for their pivots to rotate. Modern watch jewels are made of synthetic sapphire, which are tremendously hard (a 9 on the Mohs hardness scale, just below diamond), but that also makes them extremely brittle. A little too much pressure and they shatter, just like this!

Watchmakers adjust jewels using a press that can move the stones by hundredths of a millimeter at a time. Endshakes, the up-and-down movement of watch gears, are measured in as little as 0.01 mm, so this tool is critical for their careful adjustments. Jewels themselves are friction-fit into plates with zero tolerance—that means they have to be perfectly machined—so the jeweling tool has to be just as precise.

This jewel paid the ultimate price for my clumsiness. Whoops! But everyone has to start somewhere.