Olivia Bell, aged eight, will never see out her left eye again after doctors said the stone split her left pupil.
The incident happened when Olivia, from Llanrumney in Cardiff , was out playing, Wales Online reported .
Mum Samantha said police have been unable to take action against the child believed to be involved as they are under 10, which is the age of criminal responsibility.
But she hopes that by speaking out other parents and children will realise that something as simple as throwing a stone can have serious consequences.
