Rough Diamond

Diamonds are the hardest material on earth.  It is rated 10 in the Mohs scale, the highest score on the scale of hardness.  Diamonds are formed under high pressure and temperature billions of years ago at least 100 miles below the earth's surface.  

Diamonds are formed by one element - carbon.  Its crystal structure is formed in such a way that makes a diamond extremely strong.  The most common shape for rough gem quality diamond is the octahedron, which looks like two pyramids back to back.  They are then cut into different shapes and sizes like the diamonds we see in the market today.