Variation of luminosity (top-left panel), carbon excess C−O (top-right, see text for the definition), dust production rate (bottom-left) and τ₁₀ (bottom-right) of the AGB models used in the present work. The evolutions are shown with respect to the current mass of the star on the abscissa. The different lines connect a few points selected during the evolution trough the C-star phase. Open points refer to the evolution of a 5 M_⊙ star of metallicity Z = 0.001