CLOUDY spectra for PNe modeled with a range of ejecta mass at constant dust-to-gas mass ratio (top) and with a range of dust-to-gas mass ratios at constant ejecta mass (bottom). For comparison, we assume the same luminosity of 13,000L _⊙ and effective temperature of T _eff = 10⁵ K for the central star. The left panels cover a wider spectral range of 0.1–100 μm, while the right panels are centered on the [O III] 4959, 5007 ÅÅ doublet.