I successfully added a new eye color (Purple) in the geck using a new texture. I made it playable, for males and females. However, when I go to give a new NPC the new eye color I am unable to.

Is there something more I need to do?

Did you add the eye as a possible choice for the race of the NPC (characters/race/facedata) ?
You must add the new eyes (and hairs) one by one for each race. Open the eyes and the race window and drag the eyes you want to the facedata for each desired race. Then it will appear in the NPC creation window

No I didn't. Being my first new eye I thought all that I needed to do was hit Male/Female. Thanks for straightening that one up for me!