The concept of 2D elasticity of a graphene sheet together with the idea of stiffness of a single sp
3 bond have been applied to theoretical evaluating elastic properties of diverse carbon states. 2D elastic moduli have been extracted from data on elastic moduli of crystalline graphite. Stiffness of the sp
3 bond has been estimated from data on the elastic modulus of diamond. Efficiency of Van-der-Waals interaction has been taken from the elastic modulus C
33 of crystalline graphite. Characteristics of single fullerene deformability have been computed by the molecular dynamics method. Theoretical estimations have been performed for single molecular clusters, pristine fullerite, HPHT phases of polymerized C60, etc. The estimations are in good agreement with experimental data on elastic properties and nanoscale structure of carbon states. The approach is effective for establishing interrelation between nanostructure and elastic properties, for prediction and classification of nanostructure in novel carbon materials.