This is a great ink. Rich but slightly subdued, as waterproof and semi-waterproof inks seem to often be. Overall this is a very tame and reliable ink with a classy but interesting color to it. Not a boring blue ink by any means, and with just enough water resistance to satisfy. This ink seems to tame the wetter nibs that I have, but still flows very well. I rotate this ink along with Graf's Cobalt Blue and Midnight Blue.

The GvF-C inks are expensive, but IMO they're worth it. After more than fifty years of using fountain pens and a broad variety of inks, and tending personally toward more controlled while also smooth inks, I am truthfully surprised each time I use one of these inks at how far advanced they are--gorgeous colors, lubricated feel while still a controlled flow, surprisingly good shading even with a fine nib. These are excellent inks.