Ocean Depths vs Mirage Blue

How close are they?

ΔE 15.1, loose: different enough that you should pick on purpose. Mirage Blue is a little darker, warmer than Ocean Depths.

Can I use Mirage Blue instead of Ocean Depths?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Mirage Blue is a little darker, warmer than Ocean Depths.

Can I use Ocean Depths instead of Mirage Blue?

The same difference applies the other way round: Ocean Depths is a little lighter, 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.