ΔE 8.5, close: similar, with a visible difference side by side. Etherium Blue is a little darker, more saturated, cooler than Sapphire Blue.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Etherium Blue is a little darker, more saturated, cooler than Sapphire Blue.
The same difference applies the other way round: Sapphire Blue is a little lighter, more muted, warmer.
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 Sapphire Blue on the colour wheel See Etherium Blue on the colour wheel
All matches: Sapphire Blue equivalents · Etherium Blue equivalents