Some Aurora fountain pen can be refilled with Aurora ink cartridges, or an Aurora ink converter and any brand of bottled ink. Aurora ink cartridges are offered in blue or black ink. If you opt to refill with an ink converter, there is a rainbow of ink colors from which to choose. There are a few models that are "bottle fill only", like the Optima. Colorado Pen offers a huge 90ml bottle in over 30 different colors.