Fixing a watch requires skill, like performing heart surgery or taking off rollerblades without sitting down. Save some time with this Groupon.

Choose from Three Options

• $8 for watch-battery replacement for one watch valued under $500 ($17 value)
• $15 for watch-battery replacement for one watch valued over $500 ($35 value)
• $20 for $40 worth of watch repair

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Quartz: Keeping Time with Crystals

Inside your watch, a tiny crystal measures every second of the day. Read on to learn more about how quartz keeps time.

Made up of silica and oxygen, quartz is the second most abundant mineral in the earth’s crust. It's surprisingly common above the surface, too, found in everything from amethyst jewelry to digital watches. Its value in timepieces is thanks to a unique property of quartz: when cut a certain way and exposed to electricity, the crystal oscillates at a very precise frequency. This frequency provides a stable reference that the watch circuitry translates into one-second pulses, fueling the clock hands (or digital readout) so they maintain perfect time even when the orchestra conductor falls off his podium.

Before quartz, watches had to rely on intricate moving parts such as oscillating balance wheels. But such wheels can only oscillate at around 5 cycles per second. Quartz crystals, however, can vibrate up to more than 50 million times per second—offering much more precision than any mechanical counterpart.

Bonus Point

• Quartz can also generate an electric charge under mechanical pressure. In 1880, Pierre Curie—husband of Madame Marie—and his brother Paul-Jacques discovered this property, known as piezoelectricity.
• Piezoelectricity has myriad applications beyond watches. Radios, for example, use quartz to stabilize their frequency so morning-zoo hosts can't interrupt every program.