the present invention discloses size controlled and stabilized nano - aggregates of molecular ultra small clusters of noble metals and a process for the preparation thereof . the present invention discloses single source multicolor noble metal spherical and uniform nano aggregates of 10 - 22 nm made up of discrete molecular ultra small noble metal nanoclusters of 1 - 6 atoms . the musnbnc &# 39 ; s are capped with amine / dca group acting as a steric and kinetic hindrance for core growth suppressing the further autocatalysis and conversion of super critical nucleus or growth by ripening and formation of nanoparticles and thus having intense fluorescence .