The extremely rare, 10-carat Mediterranean Blue diamond could fetch a whopping $20 million at Sotheby's High Jewelry auction ...

“Any vivid blue diamond is a discovery worth celebrating, but one of this size and depth of color is a rare event,” said Quig Bruning, Sotheby’s Head of Jewelry for the Americas & EMEA.

Another nominee, Gloria Stuart who played Rose as an old woman, wore a similar oblong blue-diamond pendant from Harry Winston valued at $20 million, creating perhaps the costliest mini-trend in ...