High-quality black opal can cost over $10,000 per carat, making it one of the ... with lack of supply driving up the price. Black opal costs from $1,000 a carat to tens of thousands of dollars.

In the outlook, Petra Diamonds expects diamonds from Cullinan to fetch between $125 and $135 per carat, while those from ... after scaling back operating costs by $30 million (more than R550m ...

The average diamond price for the third tender was $101 per carat, a significant drop from $126 per carat in the first two tenders of the financial year. Petra noted that diamond pricing remains ...