Read it through once

The Kimberley crater is roomy enough to admit the Roman Coliseum; the bottom of the crater has not been reached, and no one can tell how far down in the bowels of the earth it goes. Originally, it was a perpendicular hole packed solidly full of blue rock or cement, and scattered through that blue mass, like raisins in a pudding, were the diamonds. As deep down in the earth as the blue stuff extends, so deep will the diamonds be found.