It is an industry that was supposed to be cleaned up, after the turn-of-the-millennium­ notoriety surrounding so-called blood or conflict ­diamonds—precious stones mined in African war zones ...

because of "ethical sourcing and sustainability compared to natural diamonds, given the concerns around blood diamonds." ...

It is of little wonder that England’s queens were reluctant to own the world’s most famous and expensive diamond. The story of the Koh I Noor diamond, which sits in ...