Doped Gold - Perth Mint

A leaked internal assessment revealed that the Perth Mint might be forced to repatriate $9 b worth of gold bars after masking the sale of diluted or ‘doped’ gold bullion to China. Gold bars can never be made 100 per cent pure, so there will always be some other material that makes up bullion. The industry standard is for bars to be 99.99 per cent gold, known as 'four nines' gold. Refiners keep their gold as close to 99.99 per cent as possible – because any gold over that threshold isn't paid for by the customer. The mint's processes produced 99.996 per cent pure gold, meaning about 0.006 per cent of each bar was "giveaway", so to reduce that amount, silver was added to the mint's bars. The Western Australia government-owned mint started doping its gold in 2018.

The mint saved $600k per year as a result of its doping scheme. In September 2021, the doping scheme started to unravel. Two bars violated Shanghai Gold Exchange’s requirements and included excessive silver. Up to 100 tonnes of gold supplied to the Shanghai Gold Exchange (SGE) didn't meet Shanghai’s exact purity criteria for silver content.

It wasn’t just one faulty batch, it was the majority of the gold bars produced throughout the course of the three-year doping scheme.

The mint tried to keep this knowledge from China. The Perth Mint stopped its gold doping program the moment the failed assay was detected.