Medium Rust vs Blood Chalice

How close are they?

ΔE 15.7, loose: different enough that you should pick on purpose. Blood Chalice is a little lighter, more saturated, cooler than Medium Rust.

Can I use Blood Chalice instead of Medium Rust?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Blood Chalice is a little lighter, more saturated, cooler than Medium Rust.

Can I use Medium Rust instead of Blood Chalice?

The same difference applies the other way round: Medium Rust is a little darker, 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.