ΔE 12.7, fair: the same colour family, but not a straight swap. Sky Grey is a little lighter, more muted than Worn Stone.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Sky Grey is a little lighter, more muted than Worn Stone.
The same difference applies the other way round: Worn Stone is a little darker, 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.
See Worn Stone on the colour wheel See Sky Grey on the colour wheel
All matches: Worn Stone equivalents · Sky Grey equivalents