Counterfeiting of integrated circuits (IC) has become a serious concern for semiconductor industry. It is necessary to find a robust solution which is both efficient and low cost in terms of implementation in order to detect and avoid the counterfeiting of ICs. Also, the solution must be resistant against aging and other reliability effects. In this paper we have proposed a scheme to utilize radiated Electromagnetic (EM) emission from the IC to create a fingerprint. Our proposed scheme exploits manufacturing based process variation (PV), which continues to dominate in the nanoscale technologies. We have deployed variability-aware circuit (VAC) design that generates radiated EM emission and performs realistic assessment of the PV effects. Generated EM response is treated to different encoding metrics to quantize it as a fingerprint for the IC. Latter part of the paper validates that the fingerprint is stable after the aging effects of IC. To validate our proposed scheme measurements are carried out over several FPGA boards.