What category of rock do diamonds fall under?

Diamonds fall under the category of igneous rocks, specifically as a mineral that forms under high-pressure and high-temperature conditions in the Earth's mantle. They are composed of carbon atoms arranged in a crystal lattice structure, which gives them their remarkable hardness and brilliance. While diamonds themselves are not rocks, they are often found in kimberlite and lamproite pipes, which are types of igneous rocks that can transport diamonds to the surface.