ΔE 7.7, close: similar, with a visible difference side by side. Triumphant Navy is more saturated, cooler than Amethyst Blue.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Triumphant Navy is more saturated, cooler than Amethyst Blue.
The same difference applies the other way round: Amethyst Blue is more muted, 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 Amethyst Blue on the colour wheel See Triumphant Navy on the colour wheel
All matches: Amethyst Blue equivalents · Triumphant Navy equivalents