This is also why some watches are more expensive than others, good watches use a crystal with a tighter tolerance, which is more expensive to produce.

You really don't want to change this crystal on your computer board unless you really, really know what you are doing (like you built the board from a kit). The chip which generates the clock signals can be changed programmatically to generate different speeds, so the crystal itself doesn't change… the way the crystal's base frequency is multiplied changes.

The multiplier is usually set automatically by the BIOS when the computer starts, but you can 'overclock' your system by forcing this multiplier higher. I strongly recommend you don't do this… instead of getting a faster computer, you'll burn out the slow one you won't have anymore when you have to buy a faster one anyway. If your CPU could take the extra speed, they would have already sold it with that rating.