ΔE 15.5, loose: different enough that you should pick on purpose. Karak Stone is noticeably darker, cooler than Luminous Flesh.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Karak Stone is noticeably darker, cooler than Luminous Flesh.
The same difference applies the other way round: Luminous Flesh is noticeably lighter, 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 Luminous Flesh on the colour wheel See Karak Stone on the colour wheel
All matches: Luminous Flesh equivalents · Karak Stone equivalents