Natural diamonds are rarely homogeneous. Crystals contain evidence of complicated histories of growth, changes of habit, chemistry, stages of growth and resorption. To extract genetic information recorded during diamond formation they should be studied by modern methods of microanalysis in polished plates. The best way to polish diamond to reveal internal zonation is described and the interpretation of different types of internal morphology of diamonds from cathodoluminescence imagery is given. Knowledge of the internal structures of diamonds is not only useful for scientific observations, but also allows a better determination of their likely behaviour during the cutting and polishing processes. This gives an opportunity for more economic use of individual stones during gem production.