ΔE 11.6, fair: the same colour family, but not a straight swap. Quartz Magenta is warmer than Volupus Pink. They are different kinds of paint: Citadel Volupus Pink is a one-coat contrast-style paint and Green Stuff World Quartz Magenta is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Quartz Magenta is warmer than Volupus Pink. They are different kinds of paint.
The same difference applies the other way round: Volupus Pink is cooler.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Volupus Pink on the colour wheel See Quartz Magenta on the colour wheel
All matches: Volupus Pink equivalents · Quartz Magenta equivalents