Sirenscale Green vs Beetle Green

How close are they?

ΔE 9.8, close: similar, with a visible difference side by side. Beetle Green is more muted than Sirenscale Green.

Can I use Beetle Green instead of Sirenscale Green?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Beetle Green is more muted than Sirenscale Green.

Can I use Sirenscale Green instead of Beetle Green?

The same difference applies the other way round: Sirenscale Green is 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.