How are diamonds formed? Are they formed by magma? Tell me in detail.

Diamonds are products of diamond processing.

Diamonds are the hardest and simplest gems in the world. It is a cubic natural crystal composed of carbon. Its composition is basically the same as our common coal, pencil lead and sugar. Under high temperature and pressure, carbon element crystallizes to form graphite (black), while under high temperature, extremely high pressure and reducing environment (usually anoxic environment), it crystallizes to become precious diamond (colorless).

Kimberlite, the original rock of diamond, is an alkaline ultrabasic volcanic rock, which is formed in the deep part of the earth and contains a lot of volatile components such as carbonic acid gas. This kind of rock often contains peridotite and eclogite fragments from deep earth, and its main mineral components include olivine, phlogopite, carbonate, pyroxene and garnet.

Another kind of original rock containing diamonds is called K-Mg lamprophyre, which is an overbased magnesian volcanic rock. It is mainly formed by leucite and volcanic glass, and may contain minerals such as pyroxene and olivine. Its typical origin is argyle, Western Australia.

Kimberlite (named after South African place name Kimberlite) and K-Mg lamprophyre are both produced by volcanic eruption. The rocks formed in the deep part of the earth are brought to the surface or the shallow part of the earth by volcanic activities. This magma is mostly produced in the form of rock pipes, so it is commonly called "tube ore" (that is, primary ore).