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Analysis has been performed on the results of infrared spectroscopic evaluation of nitrogen content in diamonds of various habits and relief of facets on the example of spatially disconnected primary diamond deposits of Yakutia. It has been revealed that general content of impurity nitrogen in crystals was less closely related with their habit than with specific features of surface relief of facets. Similar by surface of diamonds from spatially disconnected pipes Mir, International, Nyurbinskaya, Botuobinskaya, Zapolyarnaya, Deimos have close values of total nitrogen (N tot), therewith, but differ by nitrogen aggregation degree, quantity of tabular formations and their average size.
Availability of interrelation between mineralogical features of diamonds and content of structural nitrogen in them allows to distinguish the following groups of diamonds:
a) a group of most high-nitrogen individuals with average 900 at.ppm concentrations of nitrogen consisting of table-cut octahedrons and octahedrons with dull facets;
b) a group of high-nitrogen diamonds of various habit shapes with sheaf-like hatchure with 700-600 at.ppm concentrations of nitrogen. Octahedrons in this group of crystals have a little higher average content of nitrogen in comparison with rhombic dodecahedra and crystals of transitional forms.
c) a group of diamond crystals containing somewhat less nitrogen - about 500 at.ppm on the average. This group includes polycentric octahedrons, diamonds of transient from octahedron to rhombic dodecahedron forms with block sculpture, polycentric facets, rhombic dodecahedra both laminar and rounded with block sculpture and cryptolayered.
d) crystals with average 350-400 at.ppm contents of nitrogen. Basically these are diamonds with splintery hatchure. Octahedrons in this group are most low-nitrogen, but have somewhat higher average contents of nitrogen in this group, in comparison with crystals of transitional forms.
e) the least-nitrogen group of crystals with average 250-150 at.ppm contents. Thin-layer rhombic dodecahedra, dodecahedroids with shagreen and strips of plastic deformation (most low-nitrogen).
The distinguished similar contents of general nitrogen in diamonds with identical facet relief from deposits of different kimberlite fields and areas of the Siberian platform specify similar conditions of their formation, and testify for vertical heterogeneity of the upper mantle structure within the Siberian platform, and different depth of kimberlite formation. Difference in the degree of aggregation, concentration and dimension of crystals platelets of certain habit and relief of facets indicate that significant changes of these parameters occurred in post-growth period prior or during transportation to the surface and are the basic identification features allowing to determine affiliation of diamonds of analyzed deposits.
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