Nearly 3 years ago I wrote a review for the newly-produced Blackstone Barrister Blue Ink - part of a new line of permanent inks made in Australia (you can find that review at http://www.fountainp...-permanent-ink/). It was (and remains) a favourite of mine: a dark, strong blue that wrote well and stayed written no matter how much water you threw at the page!
My recollection is that Kevin (the proprietor of Blackstone Inks and Just Write Pens) was not entirely happy with the ink, though - because whereas his black ink relied on a nano-pigment dye, the blue relied on a dye that had iron-gall like properties (though much less corrosive). Which meant that the blue started out darkish, and went almost black with time.
Fast forward 18 months, and I found myself looking at a YouTube review of Barrister Blue, on fellow Aussie Mick L's YouTube channel (see link at bottom). Mick's sample looked substantially lighter - so I made enquiries and discovered that Blackstone had reformulated the ink using a newly-available blue nano-pigment. The ink was out of stock at the time, so it was many months later that I finally bought a new bottle - and many months more before a discussion on my old review thread prompted me to re-post.
There is also now a Blue-Black ink available from Just Write Pens (www.justwrite.com.au) and (probably) other Blackstone distributors. It took me months to procure a bottle (it was out of stock for a long time), but I now have it, and will review it - another awesome ink.
Below is a scan of the new formulation Blackstone Barrister Blue - very happy to answer questions. Disclaimer: I'm a long-time buyer from the JustWrite website, but purchased these inks at full price with my own funds.
And a close-up of the Water Test:
Mick L's YouTube review from October 2017: