Karak Stone vs Beast Hide

How close are they?

ΔE 7.1, close: similar, with a visible difference side by side. Beast Hide is a little darker, more muted than Karak Stone.

Can I use Beast Hide instead of Karak Stone?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Beast Hide is a little darker, more muted than Karak Stone.

Can I use Karak Stone instead of Beast Hide?

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

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.