ΔE 19.0, loose: different enough that you should pick on purpose. Skink Blue is a little lighter, more muted, cooler than Hydra Turquoise.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Skink Blue is a little lighter, more muted, cooler than Hydra Turquoise.
The same difference applies the other way round: Hydra Turquoise is a little darker, 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.
See Hydra Turquoise on the colour wheel See Skink Blue on the colour wheel
All matches: Hydra Turquoise equivalents · Skink Blue equivalents