Pink Star, the most expensive diamond

Natural pink to red diamonds are among the rarest and most desired fancy colored diamonds. How they form is still a mystery, but the scientists have observed that the majority of pink diamonds have a 550 nm absorption band, which indicates that shear stress and deformation of the crystal structure had occurred while the diamond was deep within the earth. 

The Pink Star diamond is one of the most expensive gems to be sold to date. This rare diamond that weights 59.60 ct was sold at a price of $ 71 million as announced by GIA. It cost around USD 1,208,053.69 per carat.