Royal Cloak vs Seraphon Blue

How close are they?

ΔE 9.8, close: similar, with a visible difference side by side. Seraphon Blue is more saturated, warmer than Royal Cloak.

Can I use Seraphon Blue instead of Royal Cloak?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Seraphon Blue is more saturated, warmer than Royal Cloak.

Can I use Royal Cloak instead of Seraphon Blue?

The same difference applies the other way round: Royal Cloak is more muted, 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.