Diamonds are almost solely composed of carbon. Trace amounts of other elements, such as boron or nitrogen, can be found in a diamond. The carbon in a diamond is in its most concentrated form. Diamonds are extremely dense due to being formed under extreme pressure (about 1,000,000 pounds/in2) and at great depth, in the mantle of the Earth.
The gems travel to the Earth’s surface via magma, or molten rock. The magma erupts in volcanoes and beneath the volcanoes, carrot shaped pipes form. Within these pipes (known as kimberlite or lamporite) are rock, volcanic material and sometimes diamonds.
Diamonds have the hardest known surface (only another diamond can scratch a diamond’s surface). They also are relatively resistant to fracturing (although they will, neatly, along certain planes) and are transparent due to their unique arrangement of carbon atoms.
The pattern atoms form in a mineral is known as the crystal structure and it defines the properties of a mineral. So what is it about the crystal structure of diamonds that makes them strong and see through?
First some basics—there are six protons and six electrons around the nucleus, or center, of a neutral carbon atom. Of those six electrons, four are known as valence electrons. These electrons are capable of bonding with other atoms. In a diamond, all four of these electrons have linked themselves to other available electrons in other carbon atoms.
The result of all these available electrons connecting is known as a tetrahedral unit and it forms the strongest type of known bond, a covalent bond. It creates a repeating cube-like structure of eight attached atoms in diamonds. It is this repeating bond that gives a diamond its hardness and strength.
Sell Diamonds - Back to the Learning Index