Isy Neuman hands a plastic box across a coffee table in the courtyard of a Johannesburg hotel. The credit card-sized container holding 10 diamonds has taken almost half his life to develop and will, he claims, turn the precious stones into something they have never yet been – a standardised tradeable commodity.

The idea of commoditisation of diamonds has met with resistance in the past. Diamond pricing takes place behind closed doors and lists of prices are rarely published. Many retailers say a more structured market could threaten the emotional allure of diamonds.