Liquid ink writing pen with visible tip

A writing pen of the type employing low viscosity liquid ink retained in a reservoir in the pen body by means of a capillary collector element. The nib of the patent is color coded to correspond with the color of ink contained within the pen. A closure cap for the pen is formed with large openings in the region surrounding the color coded nib, to provide visual access to the colored nib when the cap is mounted on the pen body. An air passage, necessary for the reservoir of the pen to "breath", is extended to have its outlet immediately adjacent the writing tip of the pen, and the closure cap is provided with an internal sealing cup at its closed end, which is received over the writing tip and closely adjacent portions of the nib, to seal both the writing tip and the air passage, when the closure cap is in place. The color coded nib is formed by a colored sleeve, which is positioned over the projecting nib of the pen and defines one or more passages for breathing air, leading from the tip of the pen back to the capillary cartridge.