Relatively small, but slowly and perfectly formed over billions of years, the Argyle Violet diamond is so rare in color that it has its own unique diamond classification: “Fancy Deep Grayish ...

Rio Tinto (LON:RIO) unveiled Tuesday a rare 2.83-carat violet diamond, the largest of its kind ever found at Australia’s remote Argyle mine, which could sell for more than $4 million.

Rio Tinto said violet diamonds were extremely rare with only 12 carats of polished stone produced for the tender in 32 years. Sydney, Australia: A rare violet diamond, the largest of its kind ever ...