It seems Blackstone inks are a product of FPN - their origin can be traced back to 2013 when some of ink-testers (Amberlea minions) started discussng powdered inks. Soon after many of us had a chance to review / try the original SuSeMai powdered inks. The powders are gone but in the meantime they evolved into Blackstone ink concentrates and recently the line called Colours of Australia was created (based on those concentrates).
Recently new colors were added to Blackstone lineup. Mishka from BureauDirect sent me samples. Thank you
Blue Gum isn't really the color I would use on daily basis. I'm not keen on similar hues. It doesn't make me clench my teeth in pain but I don't find it enjoyable. The ink is heavily saturated and offers good level of flow and lubrication. I haven't experienced any issues like clogging or nib crud with this one.
If you like similar hues this one may be interesting to you.
Drops of ink on kitchen towel
Oxford, Jinhao 866, medium nib
Rhodia, Jinhao 866, medium nib
Midori, Jinhao 866, medium nib