Shalaxi Violet vs Ultramarine Blue

How close are they?

ΔE 6.9, close: similar, with a visible difference side by side. Ultramarine Blue is cooler than Shalaxi Violet.

Can I use Ultramarine Blue instead of Shalaxi Violet?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Ultramarine Blue is cooler than Shalaxi Violet.

Can I use Shalaxi Violet instead of Ultramarine Blue?

The same difference applies the other way round: Shalaxi Violet is 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.