Twilight Blue is a darker blue; much Darker than Nitrogen Royal Blue but it is also a similar hue to Nitrogen Royal Blue. I wouldn't call it a blue-black as it doesn't have much 'black' to it. It's just dark; underneath that darkness it is still rich, vibrant, and saturated. The ink is very well lubricated and flows rather wet. It, like, Nitrogen Royal Blue and Walden Pond Blue do tend to dry out quickly when the nib is exposed and you have stopped writing, at least quicker than you might expect. This might be to do with what appears to be a very high concentration of dye (which the other inks also have). This high dye concentration might also be responsible for the sheen.

The blue is very rich. It, like Nitrogen, leans more green than red (notwithstanding that the ink is more red than blue on some paper due to the sheen!). This is very much a blue ink, I only mean it is slightly more green than it is red. It feels like a very similar hue to Nitrogen but just darker. It shades fairly low on Tomoe River but better on Rhodia. I wouldn't call this a good shading ink.

The ink, like, it's predecessors, fairs well on cheap paper. There's spreading but not much feathering and little bleeding. This ink does smudge but performs better in the regard than Nitrogen Royal Blue does. I also found it less messy, so that's a plus!