Emma Frost is a mutant with the ability to read people's minds and can turn herself diamond. Emma was born in a wealthy family, when she was young her older brother gets furious with her father not letting his son become in charge in the next family line. That's when her powers manifested when she read her brother's mind.
When Emma grew older she became a member of the Hellfire Club as the White Queen. But Sebastian wanted Jean Grey as the new queen. After the X-Men defeated the Hellfire Club, Proffesor X recruits her to become a member of the X-Men still keeping her name.