Diamonds form 100 miles below the Earth's surface, where intense heat and pressure crystalize carbon.

Most diamonds are forged in the Earth's upper mantle at depths of 90 to 150 miles. In this region, temperatures reach at least 2,000 degrees Fahrenheit while pressures exceed 725,000 pounds per square inch. These conditions force carbon atoms to form strong covalent bonds in a cubic crystal lattice structure.Geologists identify this area as the Diamond Stability Zone. Research by the Gemological Institute of America (GIA) confirms that diamonds can remain in this zone for billions of years. Some specimens found today are estimated to be 1 to 3.5 billion years old, nearly as old as the planet itself.The journey to the surface occurs through rare volcanic events involving kimberlite or lamproite magma. These eruptions travel at speeds of up to 30 miles per hour, acting as an elevator for the crystals. If the ascent were slower, the diamonds would transform into graphite due to the decrease in pressure.The first major discovery of these kimberlite pipes occurred in Kimberley, South Africa, in 1867. This event revolutionized the diamond industry and provided scientists with a window into the deep Earth. Today, sophisticated isotopic dating of mineral inclusions allows researchers to track the specific geological history of individual stones.