A mineral composed essentially of carbon crystallized at
extremely high temperatures and pressures. In nature, diamonds form at 150 to
200 kilometers (93 to 124 miles) or more below the earth's surface. Diamond
is the hardest of all known natural substances, and forms in the cubic, or isometric,
crystal system. It ranges from colorless to a wide variety of colors. Poorly
colored or heavily included single crystals are used for industrial purposes.
For more information visit the Gemological Institute of America
Inc. http://www.gia.org/