ИСТИНА

M.V.Lomonosov deposit is the first hard rock diamond deposit in the Europe. The diamonds have unique morphological and physical properties. More than 50% of them have gem quality. The round rombododecahedra prevail. Then round tetrahexahedra follow. Octahedra are rare, but their shave in small classes (<1mm) is rather high. Cubic crystals are rare also. The diamonds have numerous sculptures and channels of corrosion. They have undergone an oxidizing solution at the final phases of crystallization under the mantle conditions. Several diamond generations (embryos, zoning, inclusions of “a diamond in a diamond” type) and traces of plastic deformation were established by a color cathodoluminescence method. It shows on complicated history of diamond formation in the mantle. Most of the crystals, according to their absorption spectra, contains many nitrogen impurity’s defects. The concentration of A-defects makes up (30-40)x1019 cm-3. The low concentration of A-defects was determined in microdiamonds. The content of IIa-type diamonds is low. N2, CO2 and H2O (up 70%) are the main fluid inclusions. It is another proof that the crystallization of the diamonds was under the oxidizing conditions. The isotopic composition varies and the content of C13 changes from -2,9 up to -22,2 %0. It shows on different carbon sources. Chemical composition of the mineral inclusions indicates on peridotitic and eclogitic paragenesis of a diamond. There are no inclusions of sulfides, wustite and native iron. Thus, the diamond crystallization of this deposit was long, with several stages and occurred under oxidizing conditions in the environment enriched by N2, CO2 and H2O. The reductive low part of the mantle didn’t take part in convergation of the mantle flow and didn’t give the microdiamonds in association with native iron, troilite and wustite as embryos to the region of birth of diamond-bearing magmas at upper parts of the mantle.