gold doping

The Perth Mint has been in the headlines, accused of money laundering and of gold doping. The second charge needed explanation.  It seems that gold bullion cannot be 100% pure gold. There is always a little non-gold in it but the general standard maintained is that it is 99.99 per cent gold.

This is referred to as the four nines standard.

The Perth Mint found itself making 99.996 pure gold which, in effect, was giving .006 of gold free to the customer since it was in excess of the four nines standard. To bring their gold back closer to the standard they added a little silver. They doped their gold with silver. Again this is standard practice.  Their problem was that the Shanghai Gold Exchange required a slightly higher standard.  They would not allow more than .005 of silver.  So the Perth Mint is now in trouble.