We report the synthesis of nano-scaled alumina of varied dimensions through a novel optimized processing of aluminum nitrate. The X-ray diffractometry confirmed the formation of X- and γ- phases of alumina particles in the nano region, depending on the annealing conditions during processing. Subsequently, a detailed microscopic investigation revealed the morphological alterations and crystallographic information even at lattice scale. The presence of different bonds and band energies were investigated by employing infra-red and photoluminescence spectrometry, respectively. The evolution of fascinating microstructure, phase formations and optical bands has been presented and discussed to elucidate the systematic evolution of different crystalline phases (α and γ) from an amorphous alumina with increased annealing temperature.