Benitoite is a medium blue-grey, it could be called an unsaturated blue-black.
In large swabs the ink looks much darker, turning almost black when concentrated.
Let's take a look at how the ink behaves on fountain pen friendly papers: Rhodia, Tomoe River, and Leuchtturm.
Dry time: 30 seconds
Water resistance: Medium-about half the ink washed away, but it might still be readable.
Show through: Medium
On Staples 24 lb copy paper the ink ink did pretty well, no bleeding and feathered only in the larger nib sizes.
I used a TWSBI Eco Transparent Blue with a medium nib on Tomoe River paper. The ink had a slightly dry flow.
Overall, it’s a nice ink. I love blue-black inks, but this one is a bit on the light side. I like it best in wetter nibs since it is a bit dry.
Disclaimer: A sample of this ink was provided by Pen Boutique for the purpose of this review. All photos and opinions are my own. This page does not contain affiliate links, and this post is not sponsored in any way.