ΔE 10.4, fair: the same colour family, but not a straight swap. Coldstone Grey is a little lighter, more muted than Deep Grey.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Coldstone Grey is a little lighter, more muted than Deep Grey.
The same difference applies the other way round: Deep Grey 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 Deep Grey on the colour wheel See Coldstone Grey on the colour wheel
All matches: Deep Grey equivalents · Coldstone Grey equivalents