Elizabeth Taylor really does have violet eyes. They appear more violet in some movies than others due to the colorization of the film.
Liz Taylor was born with purple eyes, and this color appears when the cornea rods take half the recessive gene of blue eyes, and then mixes it with a bit of brown genes.
Violet eyes are extremely rare, only few people in the world have them.
The eye color was one of the reasons Elizabeth Taylor became so famous.
Here are a few pictures of Liz Taylor's purple eyes.