Now turn lead into gold

i sat with my nephew and told him a story, when he saw something tattooed deep into my chest ;" Uncle what is that?" he asked. I feel into sorrow and remembered the pain ;" Its something you never have to live through again " I replied.
He asked yet again;" Uncle what is that " and i held my hand close to my chest;" Its a stone that turns lead to gold " I replied.
My nephew looked me in the face and said;" Why the sad face? " i sat quiet for a while.. " Cause it makes men into monsters " was the only thought that came to my mind.