Wraithbone vs Cloudy Sky

How close are they?

ΔE 9.7, close: similar, with a visible difference side by side. Cloudy Sky is a little lighter, warmer than Wraithbone.

Can I use Cloudy Sky instead of Wraithbone?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Cloudy Sky is a little lighter, warmer than Wraithbone.

Can I use Wraithbone instead of Cloudy Sky?

The same difference applies the other way round: Wraithbone is a little darker, cooler.

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.