This is a used Franklin Cristoph Model 66 in Jade Green.
About the 66:
The 66 is an SEO model, only made in periodic special editions.
♦ Features our special block threads at the end of the grip section. These smoother feeling threads are out of the way of your fingers. Placing the threads at this spot limits the amount of air within the cap chamber, thereby helping to eliminate dry out. The design of the block threads also releases the air when you unscrew so as to not create a suction effect on the ink.
♦ Each pen can be filled via long or short international cartridge, by a converter, or via an eyedropper. We recommend a little silicone grease on the threads if you use it as an eyedropper.