A comprehensive study of the Carnian diamonds of the Bulkur anticline in the northeastern Siberian craton has been conducted. Two most common diamond types in the Bulkur area have been identified: scarred dodecahedroids and crystals of varieties V-VII according to the Yu.L.Orlov classification. These groups are characterized by a lighter carbon δ13C isotope composition from –19.6 to –24.7 ‰, differing in morphology, concentration and forms of nitrogen aggregation, and composition of melt inclusions. Submicroscopic inclusions in diamonds of these groups have been studied for the first time. Such inclusions in dodecahedroids are of less ferruginosity (12 and 31 wt.% FeO on average) and more enriched in potassium (5.5 and 1.7 wt.% K2O on average) compared to diamonds of varieties V-VII. It is concluded that the studied dodecahedroids with scars from the Carnian deposits of the Bulkur anticline represent a separate type of diamonds characteristic to the northeast of the Siberian platform. It is assumed that the primary sources are Precambrian in age and that the diamonds entered the Triassic and younger placers as a result of the erosion of Proterozoic coastal-marine deposits within the Precambrian protrusions, in particular on the Olenek uplift.