CL image of a diamond from the Bultfontien kimberlite pipe, Kimberly, South Africa.

The image shows the complex growth pattern of the diamond, with alternating phases of 'cuboid' (rounded shapes) and octahedral (flat / square) growth. The growth zones reflect small variations in Nitrogen composition (0 to 1226 ppm).

The image represents an area approximately 3.3 mm wide.

Image courtesy of Prof. Ben Harte and Dr. John Craven,

Geology and Geophysics, University of Edinburgh.