Part 1 - How are the diamonds formed?
Diamonds are a crystallized form of carbon that grows from a primary carbon source subjected to very high temperatures and pressure. Almost all commercially minable diamonds are formed in an area of the earth's mantle about 150 kilometers below the surface. This area is often known as the diamond stability zone, where temperatures are above 1000 degrees Celsius. There is also tremendous pressure at these depths, between 45- and 60-kilobars. In nature, this process can take anywhere from one billion to over three billion years.