Diamond samples of various origins containing NV centers were studied using optically detected magnetic resonance (ODMR) and photoluminescence (PL) methods. It is shown that various impurities and deformation-induced defects can significantly influence the crystal environment and properties of NV centers. This influence is reflected in such characteristics as the distribution of NV centers throughout the crystal volume, their charge state (the ratio of neutral to negatively charged NV centers), mechanical stresses and strains in their crystalline environment, interaction with a nitrogen donor, which affects their coherent properties, and their orientation within the diamond lattice.