The hardest substance available on earth is A. Gold B. Iron C. Diamond D. Platinum

Diamond as the name is derived from the Greek word ''adamas'' means unbreakable. It is the most sought after element in jewelry. The hardness of diamond and its high dispersion of light giving the diamond it's characteristic "fire" make it useful for industrial applications and desirable as jewelry. Diamonds are such a highly traded commodity that multiple organizations have been created for grading and certifying them based on the "four Cs", which are color, cut, clarity, and carat.