Cygnar Blue Base vs Blue Violet

How close are they?

ΔE 15.5, loose: different enough that you should pick on purpose. Blue Violet is much more muted, warmer than Cygnar Blue Base.

Can I use Blue Violet instead of Cygnar Blue Base?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Blue Violet is much more muted, warmer than Cygnar Blue Base.

Can I use Cygnar Blue Base instead of Blue Violet?

The same difference applies the other way round: Cygnar Blue Base is much more saturated, 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.