A series of different nano-sized silver particles has been prepared using r.f. magnetic plasma co-sputtering apparatus. A combination of high-resolution lattice images and optical diffractograms has been used to characterize the atomic structures during nucleation and growth of silver particles embedded in a silica matrix. For particles with diameter of 2 ∼ 5 nm, most have single crystal structures, but some have singly twinned morphologies and a few have multiply twinned morphologies. In those particles, there are many defects such as dislocations, stacking faults, twin boundaries and lattice fringe bends. For particles with diameter of 5 ∼ 9 nm, we can detect some single crystals, singly twinned particles and multiply twinned particles including decahedral and icosahedral particles. Anomalous meta-stable structured particles with 90° cross {111} lattice fringes have been also found. For particles with diameters of larger than ∼ 9 nm, most have multiple lamellar twins and sometimes there are macroscopically irregular shaped particles.