Petra Mining announces the sale of a 39.34 carat type 11b, blue diamond. This diamond was recovered in the Cullinan mine in Gauteng, South Africa in April 2021. The Cullinan mine is renowned for producing large blue diamonds. The gem will be sold on auction in July and viewings will be held in Antwerp, Dubai, Hong Kong and New York. It is the presence of boron in the diamond that gives the diamond its colour and this gem is superior both in colour and clarity. The gem could fetch a sum exceeding R350 million.