Interactive Pen Displays and Tablets. Koh-I-Noor Nexus Studio Pens. Pros: Colors are superb and varied, design is unique and intriguing, good weight, has intrinsic quality in writingCons: Many are dead on arrival from several orders, seemingly random and short lifespan, On writing quality and flow: each color has a different consistency ink; ebony has the most flow, almost too much in comparison to the others.
I believe one of the darker sepia colors is also very juicy. Winsor & Newton Drawing Ink Set of 8 Pigmented Inks in 14ml Resealable Bottles - Lowest Prices on Ink Sets at Utrecht. Winsor & Newton drawing inks have been used by artists since they were first introduced in the 1890's.
Today, as back then, they are revered for their brilliant colors. Winsor makes these colored inks with soluble dyes in a shellac solution which means you can combine them to make your own optical color mixtures as well as dilute them with distilled water to reduce the color strength or increase its transparency. The inks are fast drying, water resistant & transparent and most artists apply them using dip pens or watercolor brushes.