In 2011, the world’s most expensive diamond ring was sold for nearly 11 million dollars. This rare pink diamond ring has set a new first in the Guinness Book of World Records. The pink diamond boasts 5 carats; has two white diamonds; and is owned by billionaire Laurence Graff. Why so pricey? Pink diamonds are generally found only in lower carat weights. A diamond of this pure color and magnitude is most rare and therefore, unbelievably expensive.