The rare 9.46 ct. blue diamond found in a Botswana mine snared $4.5 million at a Nov. 26 auction conducted by mine owner Lucara.

That works out to $477,272 a carat.

The rough Type IIb stone, which will likely polish out to a fancy blue with VVS1 or better clarity, was found at the company’s Karowe mine in north-central Botswana.

Also included in the sale was a second small blue diamond weighing 0.64 cts., which sold for $24,500, or $38,282 per carat.

JCK