Aqua Alchemy vs Caribbean Blue

How close are they?

ΔE 8.4, close: similar, with a visible difference side by side. Caribbean Blue is more muted, cooler than Aqua Alchemy.

Can I use Caribbean Blue instead of Aqua Alchemy?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Caribbean Blue is more muted, cooler than Aqua Alchemy.

Can I use Aqua Alchemy instead of Caribbean Blue?

The same difference applies the other way round: Aqua Alchemy is more saturated, 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.