Stipula are better known for making pens than ink, a situation they do very little to address in their various web presences; it appears only on their store-front, and they say little about it apart from describing the colours. One suspects that it is made for them by an outside party. They’ve been at it for a while, it seems, as the oldest review of the stuff I could find was from 2005. It’s something of a boutique ink, as it’s a little expensive– unless you order it directly from Stipula, in which case it’s fantastically expensive.
Dark Blue: Something in the line of a Royal Blue, and it appears to have a fairly inconsistent nature. The person who sent me samples raved about it, and not as a result of any serious brain dysfunction. My sample was done on a slightly absorbing paper and with a broad point. I suggest comparing it to a letter the donor sent, on quite good paper and with a rather wet pen, in which it appears to a rather better advantage.