Medium Blue vs Scarab Green

How close are they?

ΔE 6.3, close: similar, with a visible difference side by side. Scarab Green is more muted, warmer than Medium Blue.

Can I use Scarab Green instead of Medium Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Scarab Green is more muted, warmer than Medium Blue.

Can I use Medium Blue instead of Scarab Green?

The same difference applies the other way round: Medium Blue 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.