Abstract
This paper is a preliminary report of studies on natural diamond crystals of the cube form. Setting the cube such that the (100), (001) and (010) faces are equally inclined to the line of the viewing instrument (microscope), the usual appearance of the crystal as a rough, pitted, non-lustrous lump undergoes a veritable transformation and its structure unfolds itself. Trigons come into view at different places in the body of the crystal. The spectacle recurs whichever of the eight cube corners be pointing towards the microscope. The cube is therefore formed by a layer-growth mechanism and the layers are in the (111) plane. The symmetry of the structure requires an inter-lacing of layers and this involves twinning.

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