Diamonds from the Siberian Platform have been studied in terms of their polygenesis, specifically their origin from different types of primary sources. Five groups of diamonds have been distinguished which might have originated from different sources, and their distribution over the platform has been shown. The sources of two groups of diamonds (kimberlitic and impact) are known. The former originated from Phanerozoic kimberlites, and the latter, from astroblemes. For the other groups, nonkimberlitic sources are suggested, including Precambrian ones.

Carbonado and yakutite are both porous aggregates of polycrystalline micrometre-size diamond, with very different characters from those of monocrystalline diamond. The genesis of carbonado is very controversial, whereas yakutite is thought to have been formed by meteorite impact. Neutron activation analyses of trace elements in carbonado and yakutite indicate that their rare earth element (REE) abundance patterns have common characteristics: heavy REEs are not much depleted and a negative Eu anomaly is observed. These patterns are quite different from those of kimberlite and monocrystalline diamond and are similar to those of crustal materials such as shale, supporting the hypothesis of a crustal origin for carbonado and yakutite.

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Results of comparative complex investigation are provided for diamonds from primary bodies of Mirny kimberlite field, among which three groups are distinguished sharply differing by typomorphic features of crystals, related with three separated in time phases of diamondiferous magmatism (I — vein A-21; II— pipes Taezhnaya and Amakinskaya; III — pipes Mir, International, XXIII-rd CPSU Congress, Dachnaya and Sputnik). For the first earliest group low content of octahedral is typical, with prevalence of individuals of rhombic dodecahedral habit; the second group is noted for approximately equal ratio of octahedral and rhombic dodecahedral habit crystals; sharp prevalence of coarse-laminar crystals of octahedral and transitive from it to rhombic dodecahedral habit is characteristic for the third group of most high-productive diatremes. Utilization of typomorphic features of crystals for reconstruction of exogenous history of diamonds on the way from primary sources to the places of modern location in placers, for paleogeographial reconstructions of ancient productive thick layers' reconstructions and clearing out directions of diamondiferous material drift, which will promote prospecting of their primary sources, has important significance.

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