Sparkling Amethyst vs Aluminium (Metal.)

How close are they?

ΔE 36.6, loose: different enough that you should pick on purpose. Aluminium (Metal.) is noticeably lighter, much more muted than Sparkling Amethyst.

Can I use Aluminium (Metal.) instead of Sparkling Amethyst?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 37). Aluminium (Metal.) is noticeably lighter, much more muted than Sparkling Amethyst.

Can I use Sparkling Amethyst instead of Aluminium (Metal.)?

The same difference applies the other way round: Sparkling Amethyst is noticeably darker, much more saturated.

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.