PRECIOUS METALS - Karat Unit of Fineness - The fineness of gold in coins, bars or jewelry is commonly measured in "karat" - parts per 24 – where 24 karat = 100 %. 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.

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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 

https://www.engineeringtoolbox.com/carat-fineness-precious-metals-d_1749.html