Start Picture of carbon dating

Picture of carbon dating

These conditions are met in two places on Earth; in the lithospheric mantle below relatively stable continental plates, and at the site of a meteorite strike.

In contrast, eclogitic diamonds contain organic carbon from organic detritus that has been pushed down from the surface of the Earth's crust through subduction (see plate tectonics) before transforming into diamond.

This is because cratons are very thick, and their lithospheric mantle extends to great enough depth that diamonds are stable.

Not all pipes contain diamonds, and even fewer contain enough diamonds to make mining economically viable.

During eruption these pipes are open to the surface, resulting in open circulation; many xenoliths of surface rock and even wood and fossils are found in volcanic pipes.

Diamond-bearing volcanic pipes are closely related to the oldest, coolest regions of continental crust (cratons).

An alternative, and completely different growth technique is chemical vapor deposition (CVD).

Several non-diamond materials, which include cubic zirconia and silicon carbide and are often called diamond simulants, resemble diamond in appearance and many properties.

In particular, under oceanic plates the temperature rises more quickly with depth, beyond the range required for diamond formation at the depth required.