ΔE 15.2, loose: different enough that you should pick on purpose. Hydra Turquoise is a little lighter, more saturated, warmer than Cobalt Alchemy.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Hydra Turquoise is a little lighter, more saturated, warmer than Cobalt Alchemy.
The same difference applies the other way round: Cobalt Alchemy is a little darker, 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 Cobalt Alchemy on the colour wheel See Hydra Turquoise on the colour wheel
All matches: Cobalt Alchemy equivalents · Hydra Turquoise equivalents