“A polished fragment of fibrous diamond coat surrounding colorless octahedral diamond core, shown in transmitted light. The dark cloudy zone is made up of thousands of micron-scale mineral and fluid inclusions. They are trapped between diamond fibers, which are aligned along {111} directions. The outer rim of the coating is more transparent because it contains fewer inclusions, but it marked by orange hematite staining that extends from surface cracks. The bottom edge (horizontal) is broken, and captures a small bit of the transparent core of the diamond. The two edges running at ~45° diagonals are cuboid growth surfaces. Scale bar in upper left is 1 mm. ”