Karak Stone vs Resurrection Flesh

How close are they?

ΔE 15.7, loose: different enough that you should pick on purpose. Resurrection Flesh is more muted, warmer than Karak Stone.

Can I use Resurrection Flesh instead of Karak Stone?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Resurrection Flesh is more muted, warmer than Karak Stone.

Can I use Karak Stone instead of Resurrection Flesh?

The same difference applies the other way round: Karak Stone is more saturated, 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.