Natural Cristal vs Natural Quartzo?

What's the difference between Natural Cristal and the Natural Quartzo?

Here you see the comparison..

Comparison of the Natural Cristal (Crystal) and the Natural Quartzo (quartz)

 

See the difference between the Natural Cristal (left) and the Natural Quartzo (right)

The Natural Cristal is slightly less noticeable on the limbal ring. But just a bit darker then the Hidrocor Cristal. 

Natural Cristal on the dark brown eyes.