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Precious Metals
Karat Unit of Fineness
Units of fineness - Karat
The fineness of gold in coins, bars or
jewelry is commonly measured in "karat" - parts per 24 - where
· 24 karat =
24/24 = 1 = 100 % = 1000.00 o/oo
· 18 karat =
18/24 = 0.75 = 75 % = 750.00 o/oo
· 14 karat =
14/24 = 0.583 = 58.3 % = 583.33 o/oo
· 8 karat = 8/24
= 0.333 = 33.3 % = 333.33 o/oo
Pure gold is yellow in color.
Gold is commonly alloyed with silver,
copper, nickel and zinc.
White gold is an alloy with nickel,
copper and zinc.
Note that
· 24 karat gold - 100%
- very soft, not recommended for jewelry
· 22 karat gold - 91.7%
- soft, not recommended for jewelry
· 18 karat gold - 75% -
recommended for fine jewelry
· 14 karat gold - 58.3%
- used in average jewelry
· 12 karat gold - 50% -
not acceptable in jewelry
· 10 karat gold - 41.7%
- the lowest limit for products in "real" gold
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