ΔE 12.9, fair: the same colour family, but not a straight swap. Medium Blue is a little lighter, more muted, cooler than Lapislazuli.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Medium Blue is a little lighter, more muted, cooler than Lapislazuli.
The same difference applies the other way round: Lapislazuli is a little darker, more saturated, warmer.
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 Lapislazuli on the colour wheel See Medium Blue on the colour wheel
All matches: Lapislazuli equivalents · Medium Blue equivalents