We present large-eddy si mulations (LES) of turbulent mixing at a perturbed, spherical interface separating two fluids of differing densities and subsequently impacted by a spherically imploding shock wave. This paper focuses on the differences between two fundamental configurations, keeping fixed the initial s hock Mach number ~1.2, the density ratio (precisely IAol ~ 0.67) and the perturbation shape (dominant spherical wavenumber .f 0 = 40 and amplitude-to-initial radius of 3 %): the incident shock travels from the lighter fluid to the heavy fluid or, inversely, from the heavy to the light fluid. After describing the computational problem we present results on the radially symmetric flow, the mean flow, and the growth of the mixing layer. , vol. 748, 2014, pp. 113-142). A wave-diagram analysis of the radially symmetric flow highlights that the light-heavy mixing layer is processed by consecutive reshocks, and not by reverberating rarefaction waves as is usually observed in planar geometry. Less surprisingly, reshocks process the heavy-light mixing layer as in the planar case. In both configurations, the incident imploding shock and the reshocks induce Richtmyer-Meshkov (RM ) instabilities at the density layer. However, we observe differences in the mixing-layer growth because the RM instability occurrences, Rayleigh-Taylor (RT) unstable scenarios (due to the radially accelerated motion of the layer) and phase inversion events are different.A small-amplitude stability analysis along the lines of Be ll (Los Alamos Scientific Laboratory Report, LA-132 L, 1951 ) and Plesset (J. Appl. Phys., vol. 25, 1954, pp. 96-98) helps quantify the effects of the mean flow on the mixing-layer growth by decoupling the effects of RT/RM instabilities from Be ll-Plessel effects associated with geometric convergence and compressibility for arbitrary convergence ratios. The analysis indicates that baroclinic instabilities are the dominant effect, considering the low convergence ratio (~2) and rather high ce > 10) mode numbers considered.