Since the pure metal is too soft to stand up under the punishment it gets in everyday wear, it is usually alloyed with other metals, such as silver, copper, nickel, and zinc. These can be chosen to give the gold its popular tints of yellow, white, green, and red while they increase its hardness. The quantity of gold in an alloy is indicated by the term “karat.” Pure gold is 24 karat. Fourteen-karat gold, for instance, contains 14 parts gold and 10 parts of other metals to make a total of 24 parts. Sometimes gold diamond rings financing is graded as to its “fineness,” based on how many parts out of 1000 are gold. An alloy of 85 percent gold and 15 percent copper would be 850 fine. Yellow gold alloys contain silver, copper, and zinc. White gold has nickel instead of silver. Red-gold tints are produced by using more copper and less silver than in yellow gold. Green-gold alloys require the reverse: more silver and less copper than in the formula for yellow gold