Fineness, or purity, refers to the gold content in bars, coins or jewelry. Also known as Millesimal fineness, it is indicated in 1000 parts of the whole weight. Bullion gold coins have commonly a fineness of .999 (e.g. George the Victorious) and .9999 (e.g. Maple Leaf). The gold market accepts gold bars only up to a purity of .9999 (four nines).
The picture shows the fineness of the Canadian Gold Maple Leaf, one of the most popular bullion coins.
In the 19th century other indications of the gold purity were used, such as karat (carat in non-North American writing) and lot. Nowadays, karat is mostly used for jewelry. In international trade, gold is sold with a fineness of .995, as a 12,44kg “Good Delivery bar”.
Gold smiths commonly produce jewelry with a fineness between 585 and 999. Industrially produced jewelry has a purity of between 333 and 750. The remaining part of the content consists of silver, copper, iridium, or tungsten which can give the metal alloy vastly different characteristics, regarding hardness and color as opposed to pure gold.
The purest gold bar ever produced has a fineness of .999999. It was refined by the Perth Mint in 1958. The purest type of gold in the market is .99999. A special edition of the Canadian Maple Leaf is minted with this high fineness.
Gold with a purity of .999, 24 karat, is called fine gold.
There are several writings to indicate the fineness:
Common finenesses are:
- 999.9 (also known as “four nines”)
- 999 (equivalent to 24 karat, “fine gold”, “three nines”)
- 995 (standard for Good Delivery gold bars)
- 990 (“nines fine”)
- 958.3 (equivalent to 23 carat)
- 916 (22 carat)
- 833 (20 carat)
- 750 (18 carat)
- 625 (15 carat)
- 585 (14 carat)
- 417 (10 carat)
- 375 (9 carat)
- 333 (8 carat)
A fineness of .333 is the minimum standard for gold in Germany since 1884.