- Fineness
The fineness of a
precious metal refers to theratio of the primarymetal to anyadditive s or impurities. Most precious metal is used in the form of analloy . Other metals are added to increasehardness , to make the metal more practical for use in such items ascoins andjewelry , or to decrease the cost of the alloy. For example,copper is added to the precious metalsilver to make a more durable alloy for use in coins, housewares and jewelry.A traditional measure for the fineness of silver in Britain is the
mass of the amount of silver in 12 troy ounces of the resulting alloy.Britannia silver has a fineness of 11 troy ounces, 10pennyweight s, or about 95.83% silver, whereassterling silver has a fineness of 11 troy ounces, 2 pennyweights, or about 92.5% silver.In other locations fineness is measured in units of mass per thousand. In the
United States , silver coins often had a fineness of 900, meaning 90% silver and 10% copper.The fineness (or purity) of
gold is commonly measured in carats or karats. The upper end of the scale is 24 carat for 100%. Thus 18 carat = 18/24% = 75%.ee also
*
Millesimal fineness
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