ΔE 8.5, close: similar, with a visible difference side by side. Pearl Light Blue is more saturated than Runic Cobalt. They are different kinds of paint: Army Painter Runic Cobalt is an opaque base/layer paint and Tamiya Pearl Light Blue is a pearl paint, so they won’t behave the same on the model even where the colour is close.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Pearl Light Blue is more saturated than Runic Cobalt. They are different kinds of paint.
The same difference applies the other way round: Runic Cobalt is 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.
See Runic Cobalt on the colour wheel See Pearl Light Blue on the colour wheel
All matches: Runic Cobalt equivalents · Pearl Light Blue equivalents