X-ray tomographic study of spatial distribution of microinclusions in natural fibrous diamonds

X-ray tomography was used to investigate spatial distribution of micron-sized inclusions in whole natural fibrous diamonds. It is shown that in the studied samples the inclusions are almost entirely arranged along intersector boundaries, leaving individual growth sectors virtually empty despite their pronounced fibrous structure. Comparison with previous results we suggest that at least three modes of spatial arrangements of microinclusions could be present, reflecting variations in the chemical and physical properties of the growth medium. We report the existence of large, reaching several tens of microns heterogeneous inclusions. In most cases the inclusions consist of a core surrounded by a less dense material. ► X-ray tomography reveals various types of spatial distribution of microinclusions in fibrous diamonds. ► Fibrous diamonds may contain inclusions reaching several tens microns in size. ► Many inclusions are heterogeneous in composition. ► At least three different types of inclusions arrangements in diamond are recognised.