Diament

Diament, commonly called diamond, is a native crystalline form of carbon and the hardest natural material known. It ranks a 10 on the Mohs scale and has exceptional thermal conductivity, a high refractive index, and strong dispersion. Natural diamonds occur as individual crystals and as polycrystalline aggregates.

Diamond crystallizes in the cubic (isometric) system; each carbon atom forms four covalent bonds in a tetrahedral network, giving remarkable hardness and cleavage along {111} planes.

Diamonds form under high-pressure, high-temperature conditions deep in the Earth's mantle, typically at depths of about 140 to 190 kilometers and pressures of 4–6 gigapascals. They are transported to the surface through kimberlite volcanic eruptions, often within 1–3 million years. Most diamonds are over 1 billion years old.

Major producing countries include Botswana, Russia, Canada, Australia, and the Democratic Republic of Congo. Notable deposits include the Argyle mine in Australia, which produced many colored diamonds before ceasing operations in 2020.

In gem form, diamonds are valued for cut, clarity, color, and carat. Industrial diamonds are used as abrasives and in cutting and grinding tools due to their hardness and thermal stability. Synthetic diamonds, produced by high-pressure high-temperature (HPHT) or chemical vapor deposition (CVD) methods, have become common since the mid-20th century, enabling controlled color and quality.

Diamond quality is described by the 4 Cs (carat, color, clarity, cut) and color grading from colorless to yellow-brown. Environmental and ethical concerns surround some mining practices; synthetic diamonds are increasingly promoted as an alternative with potentially lower environmental impact in some cases.