How many black contact lenses are available, you may ask? There are way too many available. So here we split them into 3 groups.
Black Sclera Contacts
The white part of our eyes is called Sclera. This group of halloween/special effects contact lenses are designed to cover that white of the eye. So everytime when you open your eye, what people see there will be black, this may totally freak some people out.
Mostly black Contacts
This group of contact lenses do not fully cover sclera, some of them do extend to part of it, but many are just a little larger than Iris. These contact lenses do not change your appearance completely, but surely will give a big impression for anyone not prepared for it.
Here they come
Some black Contacts
These contact lenses contain some black elements in it, however the black portion is not majority, so other color might over-shine the black image you might be looking for. But still many people find them quite interesting to wear.