Optical properties of various carbon and graphite grains have been measured in the UV-FIR wavelength region. The structures of crystallite and degree of crystallization of the samples have been studied by means of transmission electron microscopy. The spectral index of the specimens was distributed in the range of 0.6-2.75, The correlation between the specimens has been ascertained It became evident that the degree of crystallization of carbon and graphite can be estimated from the spectral index in the far-infrared region.