ΔE 14.7, fair: the same colour family, but not a straight swap. Indigo Sky is more muted, warmer than Frostveil.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Indigo Sky is more muted, warmer than Frostveil.
The same difference applies the other way round: Frostveil is more saturated, 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 Frostveil on the colour wheel See Indigo Sky on the colour wheel
All matches: Frostveil equivalents · Indigo Sky equivalents