The diamonds found in the Popigai Astroblem are known as "impact diamonds." They're created when a meteor strikes a graphite deposit, as happened there an estimated 35 million years ago. Impact diamonds are significantly harder than normal diamonds, and are best suited for industrial or scientific use.
Given that diamonds can sell for $2,000 per karat with unusually large diamonds going for as much as $20 million, a discovery of "trillions of karats" could value this hole in the quadrillions of dollars. Of course, a diamond discovery of this magnitude is almost sure to have a serious downward impact in the per-karat price should full-scale mining operations ever begin.