For decades, shopping for uncut diamonds was a tightly scripted affair: First, persuade De Beers to add you to its list of handpicked customers. Then, 10 times a year, attend a week-long sale to buy exactly the amount De Beers offers you at whatever price it chooses.
The system, which works more or less the same at Russian rival Alrosa PJSC, gave the two miners a tight grip on their market. With the coronavirus wreaking havoc through the industry, that control is now disintegrating.
