Both Aurora and Cross offer Black and Blue fountain pen inks. These are both excellent handwriting inks and work well most fountain pens. But they are not creative. They don’t blend easily with water and only seem to have a limited reaction with bleach where the ink has been reduced in concentration.
Cross inks are allegedly made by Pelikan so here’s a link to the Pelikan standard inks I have already tested. And as you’ll see, they are very similar in behaviour
From what I can gather, the Omas production company in Italy has recently (2016) ceased manufacturing. The company had been trading pre 1930s and are well known for their distinctive octagon shaped bottle. The five colours I have got hold of are the typical Black, Blue, Turquoise, Red and a Green. One could argue that there are visual and behavioural similarities between these inks and the Caran d’Ache and Pelikan standard inks – particularly with the dramatic sheening – the exception being the Blue, for which I can’t find a European match at the moment. Creatively these aren’t for me, but they do write very nicely – and in my opinion, better than the Aurora and Cross inks.