Hopje Brown fountain pen ink made by P.W. Akkerman pen store in The Hague.
This caramel brown has good shading.
Originally made to celebrate their 100th anniversary, this ink comes in a vintage-style bottle with a narrow neck with a marble stopper, to create a well at the top to aid in filling pens.
Hopjes are a type of Dutch sweets, with a slight coffee and caramel flavor, that originated in the 18th century. (Source: Wikipedia) Ackerman