ΔE 22.5, loose: different enough that you should pick on purpose. Ink Violet is noticeably darker, more muted, warmer than Tenebris Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Ink Violet is noticeably darker, more muted, warmer than Tenebris Blue.
The same difference applies the other way round: Tenebris Blue is noticeably lighter, 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.
See Tenebris Blue on the colour wheel See Ink Violet on the colour wheel
All matches: Tenebris Blue equivalents · Ink Violet equivalents