A model for metal spherical particle formation is proposed, guided by optical kinetic data of monodisperse metal colloid synthesis. The dynamic optical response of these systems is characterized by broad bands, making their analysis difficult to interpret in terms of particles sizes. To overcome this problem, the data are analyzed in terms of a new strategy called simulated dynamic optical response. Kinetic data were generated using a silver-ethylenediamine complex reduced with isoascorbic acid as a model system. Using this strategy, it was found that autocatalytic formation of primary particles followed by a zone of very fast aggregation mechanism can describe the dominant dynamics during early stages. In later stages, the dominant mechanism switches to slower aggregation modulated by a stability factor. The presented model and identification strategy may be applied to other reaction precipitation systems to produce metal particles.