ΔE 26.3, loose: different enough that you should pick on purpose. Sapphire Blue is noticeably darker, much more saturated, cooler than Sparkling Amethyst.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 26). Sapphire Blue is noticeably darker, much more saturated, cooler than Sparkling Amethyst.
The same difference applies the other way round: Sparkling Amethyst is noticeably lighter, 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 Sparkling Amethyst on the colour wheel See Sapphire Blue on the colour wheel
All matches: Sparkling Amethyst equivalents · Sapphire Blue equivalents