By examining the diffusion of young white dwarfs through the core of theglobular cluster 47 Tucanae, we estimate the time when the progenitorstar lost the bulk of its mass to become a white dwarf. According tostellar evolution models of the white-dwarf progenitors in 47 Tucanae,we find this epoch to coincide approximately with the star ascending theasymptotic giant branch (AGB) (3.0 ± 8.1 Myr before the tip ofthe AGB) and more than ninety million years after the helium flash (with