How much does the eviolite add?

Question

What does eviolite do to your defense?

Answer 1

1,5x your original value on both Defense and Special Defense provided you can still evolve.

Answer 2

An Eviolite adds 50% to the holders defense and special defense,but only if the Pokemon can still evolve.
Bulbapedia:
Raises the holder's Defense and Special Defense by 50%, if the holder is not fully evolved.
Source:http://bulbapedia.bulbagarden.net/wiki/Eviolite#Eviolite
Hope I helped.