Sotheby's Geneva is showcasing the "Mediterranean Blue Diamond," a 10-carat gem expected to fetch $20 million at auction.

A rare 10-carat blue fancy diamond could fetch up to $20 million when it goes to auction in Geneva on May 13, auction house Sotheby’s said on Thursday. The cushion-shaped piece, known as the “ ...

"With its Royal heritage, extraordinary color and exceptional size, The Golconda Blue is truly one of the rarest blue diamonds in the world.” Golconda diamonds are among the oldest and most ...