Weathered Stone vs Light Blue RLM78

How close are they?

ΔE 12.9, fair: the same colour family, but not a straight swap. Light Blue RLM78 is a little lighter, more saturated than Weathered Stone.

Can I use Light Blue RLM78 instead of Weathered Stone?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Light Blue RLM78 is a little lighter, more saturated than Weathered Stone.

Can I use Weathered Stone instead of Light Blue RLM78?

The same difference applies the other way round: Weathered Stone is a little 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.