An excellent ink from an excellent pen. All this needs is a good paper. No green cast on bright white paper, but it can get very green on yellow paper. First wrote with this ink in my Moleskine journals and thought the bottle was mis-labled! Later, when I started using it at work on white copy paper, the blue really started to show. I had to stop using this ink in the Moleskines because of severe show through. That is what started my quest for other blue black inks. I still have not found one that has a color that I like as well as the Diamine. I tend to pass on the Montblanc / Lamy blue black due to the iron gall content (but I do like the color and they do not show through on Moleskine paper). Sheaffer Blue Black tends to be too gray for me, so I am sticking with the Dupont Night Blue for my journal for now. The Diamine Blue Black does get used when I write letters since it is just too pretty to leave in the bottle. The combination of this ink and the Phileas pen are almost perfection. If only I could find a pen that wrote like the Phileas and felt in my hand like my Dupont.

Of the four ink scans you've posted tonight (Dupont Blue, Dupont Night Blue, Diamine Royal Blue, Diamine Blue Black), this is the first one that really appeals to me. It looks like a blue black ought to look on this paper, but I'm sorry to hear that a greenish tinge appears on yellow paper. I like my blue blacks not to have any green elements.