In this study, we present a detailed Raman analysis of large-area graphene, nano-graphene sheets (>25 nm) and graphene molecules with synthetically controlled lateral dimensions between 0.76 to 1.39 nm. The integrated area ratios of D and G bands increase with the size of the molecules, when excited using two different wavelengths (532 nm and 405 nm). The D and G band positions were also found to depend on the size of the graphene molecules. The intensities of the higher-order bands (e.g., 2D, D+G, and 2G), increase for both wavelengths, as the size of the graphene molecules increases. For complete spectroscopic studies of nano- and micro-size graphitic structures, we also probed nano-graphene sheets (>25 nm) and large area graphene using the same excitation wavelengths. The reaction/synthesis time was varied to control size and crystallinity of the graphene molecules, and their corresponding spectral features including integrated area band ratios and the band positions, were thoroughly investigated. These results provide a potential route for using Raman spectroscopy as a diagnostic tool for structural characterization and understanding the reaction dynamics of graphene molecules smaller than 2 nm. Lastly, this work presents a complete representation of the spectroscopic behavior nano- and micro-sized structures (ranging from 0.76 nm to 1cm), which is currently missing from the studies of the present graphitic materials generated via ion-bombardment and other techniques.