A doré bar arrives at 85 per cent purity and leaves at 99.99. Between those two numbers sit chlorine gas, aqua regia, an electrolytic cell and a chain of custody that is now as valuable as the metal itself.
For half a century it was rational to store your gold in someone else's basement. Then the calculus of counterparty risk changed, and reserve managers started chartering aircraft.
Gold's working properties are so extreme they border on the absurd — one gram drawn into three kilometres of wire. Inside a trade where the tools have barely changed and the hands are irreplaceable.
A significant share of the world's gold is produced by people working with hand tools, informal finance and a neurotoxin. Formalisation is the stated solution. Nobody agrees on what it costs.