Sold parcel of ethically sourced diamonds came from artisanal and small-scale miners in Sierra Leone.

Decision comes after an unnamed company tried buying the miner's South African unit, which holds the mineral rights for the diamond project.

The SoW applies every time a rough or polished diamond changes hands, assuring it originates from a source compliant with universally accepted principles on human and labour rights.

The companies are billing the stone as the largest rough diamond to be shown in the United States.

The initial phase of Alrosa's study showed that kimberlite ore in its tailings could potentially absorb more CO2 than the entire company generates.

The technologies enable buyers to remotely analyze the key parameters of every diamond.