ΔE 10.9, fair: the same colour family, but not a straight swap. Lapislazuli is more saturated, warmer than Deep Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Lapislazuli is more saturated, warmer than Deep Blue.
The same difference applies the other way round: Deep Blue is more muted, 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.
See Deep Blue on the colour wheel See Lapislazuli on the colour wheel
All matches: Deep Blue equivalents · Lapislazuli equivalents