ΔE 13.5, fair: the same colour family, but not a straight swap. Graphite Grey is noticeably darker than Basilicanum Grey.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Graphite Grey is noticeably darker than Basilicanum Grey.
The same difference applies the other way round: Basilicanum Grey is noticeably lighter.
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 Basilicanum Grey on the colour wheel See Graphite Grey on the colour wheel
All matches: Basilicanum Grey equivalents · Graphite Grey equivalents