ΔE 19.1, loose: different enough that you should pick on purpose. Amethyst Purple is noticeably lighter, warmer than Amethyst Alchemy.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Amethyst Purple is noticeably lighter, warmer than Amethyst Alchemy.
The same difference applies the other way round: Amethyst Alchemy is noticeably darker, 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 Amethyst Alchemy on the colour wheel See Amethyst Purple on the colour wheel
All matches: Amethyst Alchemy equivalents · Amethyst Purple equivalents