Nine (purity)
Nines are an informal, yet common method of grading the purity of very fine precious metals such as platinum, gold and silver. Based on the system of millesimal fineness, a metal is said to be one nine or one nine fine if it is 900 fine, or 90% pure. A metal that is 990 fine is then described as two nines fine and one that is 999 fine is described as three nines fine. Thus, nines are a logarithmic scale of purity for very fine precious metals. The nines scale is also sometimes used in describing the purity of bottled gases.
Nines are used in a similar manner to describe computer system availability.
See also
This article is issued from Wikipedia - version of the Sunday, June 21, 2015. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.