LBMA USD morning price fixings ($US per troy ounce) since 2001
Gold price per ounce in USD since 1968, in actual US$ and 2006 US$Like other precious metals, gold is measured by troy weight and by grams. When it is alloyed with other metals the term carat or karat is used to indicate the amount of gold present, with 24 karats being pure gold and lower ratings proportionally less. The purity of a gold bar can also be expressed as a decimal figure ranging from 0 to 1, known as the millesimal fineness, such as 0.995 being very pure.
The price of gold is determined on the open market, but a procedure known as the Gold Fixing in London, originating in September 1919, provides a daily benchmark figure to the industry. The afternoon fixing appeared in 1968 to fix a price when US markets are open.
The high price of gold is due to its rarity. Only three parts out of every billion (0.000000003) in the Earth's crust is gold.