But of course!

They use diamonds to cut diamonds

Diamond is usually cut using high pressure water and other diamonds

If you just want to break it, you can use anything. You just need enough force.

Diamonds are created with a point

From what I understand, diamond is rather easy to cut, but damn near impossible to crush.

There is a difference between hardness and toughness. A hard (strong) object requires a lot of force to break it but it WILL break. A tough object deforms without breaking. An object can indeed be both hard and tough, but diamond is only hard. Also, diamonds (any crystal really) are easy to cut along their shear planes, which are defined by the lattice structure of the crystal. A diamond can also be ground down abrasively by materials softer than itself, this happens by knocking off high points sticking out from the surface of the diamond (which are weaker because they are sticking out). Furthermore, you can polish a diamond using fire, essentially burning off the surface of the diamond, which is just a form of carbon after all.

Then how do you break Nokia?