This thick piece of cleavage could have been separated by the force of nature or in a cleaver’s shop.

Diamond cleavage would not qualify as an exception to the rule since it is not a whole stone but rather a piece of a whole stone that has been divided from its original state. Due to the forces of nature, many times rough is split (cleaved) before it is discovered. The flat triangular pieces are discounted depending on their depth. Thicker pieces can be used to make triangular step cuts or trillions.