ΔE 27.8, loose: different enough that you should pick on purpose. Turquoise is noticeably lighter, much more saturated, cooler than Coal Black.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 28). Turquoise is noticeably lighter, much more saturated, cooler than Coal Black.
The same difference applies the other way round: Coal Black is noticeably darker, much more muted, 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.
See Coal Black on the colour wheel See Turquoise on the colour wheel
All matches: Coal Black equivalents · Turquoise equivalents