We report for the first time the observation of a finite wave vector peak in the scattering pattern from a dense solution of aggregating colloids. Measurements have been conducted under isopycnic conditions and at various monomer concentrations. The scattered intensity S (q) scales according to a universal law, S(q/qm), in close analogy with spinodal decomposition dynamics (qm is the position of the scattered peak). Although for spinodal decomposition, d is equal to 3, here, we measured d=df, the fractal dimension of the colloidal clusters. We also observed that S(q) attains a terminal shape. The position of the peak in this terminal phase scales linearly with the initial monomer concentration, as predicted by a simple model.