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  = 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 

Download and print Karat vs. Pure Gold Content Chart