The diamond trade has traditionally been secretive and unregulated with gems passing hands many times on the journey from mine to jeweller. With practically no means to differentiate diamonds from different areas, the industry has been open to smuggling and illicit dealing. In the 1990s, it emerged that rebel fighters were trading diamonds for money and weapons to wage war in Angola, Sierra Leone and the Democratic Republic of Congo (formerly Zaire). The gemstone linked with love and purity was in fact funding rape, murder and persecution.

Activists estimate that, at its peak, the trade in “conflict diamonds” made up as much as 15 per cent of the pound;4.9 billion a year world trade in rough diamonds. A campaign, started by the group Global Witness, called for diamond buyers to demand evidence of a gemstone’s provenance.

In 2000, the South African government brought together representatives from the industry and governments in an effort to find ways to certify “clean” diamonds. The Kimberley Process Certification Scheme came into effect in 2003, required the 40-plus participating governments to introduce tougher diamond regulations.