Diamonds from M.V. Lomonosov deposit are divisible into three groups on their morphological and structural features. The first group is represented by the high-temperature crystals with minor signs of dissolution. Second, the dominant one, is relatively low-temperature. It includes dodecahedroids, that are strongly dissolved crystals. The third group contain low-temperature nitrogen C defects, it composed of cuboids, tetrahedrons, often cubes with no signs of dissolution.