TWSBI Diamond 580 Fountain Pen nib Stub 1.1 Fountain Pen The Diamond 580 comes with a benchmark ink-filling mechanism and has all detachable parts We felt that it was important to allow the user to disassemble and reassemble the pen and completely experience the traditional aspects of owning and using a fountain pen. Diamond 580, a classic fountain pen with a piston ink-filling system. FREE SHIPPING