Diamine Blue/Black is my first Blue/Black review. I don't know why I haven't tried any of them before. Let's see how it performs. I purchased my bottle of ink at Cult Pens.
Blue/Black is just that-inbetween blue and black. There is no sheen.
When pooled, the ink almost looks black.
Let's take a look at the ink on fountain pen friendly paper first: Rhodia, Tomoe River, and Leuchtturm.
Dry time: 32 seconds
Water resistance: Low
Show through: Medium
On Moleskine paper, which is not fountain pen friendly, there was a little bit of feathering and a fair amount of bleeding. This isn't an ink I would use on cheap paper.
Ink swabs for comparison, left to right (top to bottom for RSS): Aurora Blue/Black, Diamine Blue/Black, and Diamine 1864 Blue Black. Click here to see the Diamine inks together.
Lamy Blue-Black, Pilot Iroshizuku Shin-Kai, and Diamine Prussian Blue. All three of these are way too light to be comparable to Diamine Blue/Black
I used a Pelican 400N nib in a Pelikan m400 White Tortoise body. On Tomoe River the ink was nice and wet, so I didn't have any flow issues.
Since the nib was so wet, it put down a lot of ink, too much to see a lot of shading. If the nib had been a bit drier you would see more shading.
Overall, I think it's a nice Blue Black. I definitely think I want to try more Blue Blacks, but this one is a great starting point.
Disclaimer: I purchased this ink myself, and all photos and opinions are my own. There are no affiliate links on this page.