ΔE 25.9, loose: different enough that you should pick on purpose. Diabolic Plum is a little lighter, much more saturated, warmer than Clear Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 26). Diabolic Plum is a little lighter, much more saturated, warmer than Clear Blue.
The same difference applies the other way round: Clear Blue is a little darker, much 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.
See Clear Blue on the colour wheel See Diabolic Plum on the colour wheel
All matches: Clear Blue equivalents · Diabolic Plum equivalents