At what layer of the earth's crust are diamonds made and name of layer?

Answer 1

Diamonds do no initially form in the crust, if you are talking about craton conditions. They form in the lithospheric mantle (remember the lithsosphere is all of the crust and some of the mantle) under high pressure (~ 50 kbars) and somewhat low temperature (~900 - 1300 C). This happens under stable continental plates, as there is too much activity at plate boundaries and the oceanic crust is too thin.

Diamonds can also be formed at impact craters. These are called microdiamonds and are used as impact crater indicators, not for gem quality use.

Diamonds do NOT form in volcanoes. That is merely the geologic process the eventually brings them closer to the surface.

Answer 2

I don't think it's so much a layer, as it is a volcanic "chute" where they form. They tend to form around volcanically active areas. Which can be anywhere, and any layer(depending on the carbon left in that area, of course ).

- The Gremlin Guy -