By Erika Winters
On October 7, 2013, Sotheby's Hong Kong will auction a 7.59-carat fancy vivid blue diamond at its Magnificent Jewels and Jadeite sale. Dubbed the Premier Blue, the rare gem is the largest round-brilliant cut, fancy vivid blue diamond ever graded by the Gemological Institute of America. The internally-flawless blue diamond, which is said to be the size of a shirt button, is expected to fetch a world-record price of $19 million.
