A natural diamond is a gemstone that is formed deep beneath the Earth's surface over millions of years through a natural geological process. Diamonds are made of carbon and are formed under high pressure and temperature conditions in the Earth's mantle. Most natural diamonds are mined from the Earth's crust, although some diamonds have also been found in meteorites. Once a diamond is extracted from the Earth, it is cut and polished to create a finished gemstone that can be used in jewelry. Natural diamonds come in a variety of colors, including white, yellow, pink, blue, and green. The color of a diamond is determined by the presence of certain chemical impurities and the conditions under which it was formed.