Frostveil vs Ultramarine Highlight

How close are they?

ΔE 7.9, close: similar, with a visible difference side by side. Ultramarine Highlight is a little lighter, cooler than Frostveil.

Can I use Ultramarine Highlight instead of Frostveil?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Ultramarine Highlight is a little lighter, cooler than Frostveil.

Can I use Frostveil instead of Ultramarine Highlight?

The same difference applies the other way round: Frostveil is a little darker, 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.