Pink Nacre vs Crimson Magenta

How close are they?

ΔE 19.5, loose: different enough that you should pick on purpose. Crimson Magenta is a little lighter, much more saturated, warmer than Pink Nacre.

Can I use Crimson Magenta instead of Pink Nacre?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Crimson Magenta is a little lighter, much more saturated, warmer than Pink Nacre.

Can I use Pink Nacre instead of Crimson Magenta?

The same difference applies the other way round: Pink Nacre is a little darker, much 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.