Kaoru Koganei

Best known as Lady Diamond. Her Euphoric power is to turn her entire body into diamond, becoming almost indestructible. She can also extend her fingernails to stab or impale targets. She has the bizarre habit of eating diamonds (even biting off the finger of a woman to get her ring). She was the wife of a talented artist who gave her diamonds to make her happy, but hung himself after taking out an insurance policy. Since then she has become obsessed with making her body into a shining monument of his love for her.

from wikipedia