Gold value. The value of any quantity or mass of gold depends upon its fineness as well as its
weight. Fineness means the proportion of pure gold and usually it is expressed in thousandths.  
The coins of the United States, both gold and silver, are .900 fine, that is, nine-tenths pure metal
and one-tenth alloy, the alloy in a gold coin being one part silver and nine parts copper, while that
in a silver coin is copper.