Mining diamond = A diamond formed and mined from the earth by geological pressure and extreme temperatures deep within the earth.
Mine crystals typically form in rounded octahedral shapes, caused by conditions deep within the Earth. They are brought to the surface by volcanic eruptions that form kimberlite pipes. The typical crystal shape of a mine diamond is an octahedron. Similar to two pyramids that are connected at the bottom. Diamond growth takes place on the eight different crystal faces.