You can see where the two crystals meet in forming this macle.

The exception to the rule of every diamond containing twelve individual grains would be the macle. This would be like the Siamese twins of diamond rough. Two crystals have grown into one to form one whole. This would count as an irregular since the weight losses are generally greater. Cutting these can be an extremely arduous task due to conflicting grains where the crystals meet each other, so expect higher labor costs.