Karak Stone vs Naples Yellow Hue

How close are they?

ΔE 18.1, loose: different enough that you should pick on purpose. Naples Yellow Hue is noticeably lighter, more saturated than Karak Stone.

Can I use Naples Yellow Hue instead of Karak Stone?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Naples Yellow Hue is noticeably lighter, more saturated than Karak Stone.

Can I use Karak Stone instead of Naples Yellow Hue?

The same difference applies the other way round: Karak Stone is noticeably darker, more muted.

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.