Gold Purity

There is an aspect very interesting and attractive on gold, its purity. For many centuries people have been interested on pure gold, and was necessary to adopt a common patron so that people can use the same unit. The universal unit is called Karat and the first use of this unit was in the Mediterranean area. The Karat was used to estimate the purity of gold alloys. It must be mentioned that word Karat was initially a unit weight based on the bean seed used in Arabia. At that time, the Karat was used to weigh precious stones. Greeks employed the work Keration and some parts of Asia was popular the name Quirat. The term Karat was the final and universal name adopted to measure the gold purity. 

For a long time gold has been alloyed with other metals in order o get a metal with better mechanical properties and one aspect very interesting was the color took by the alloy. This color is influenced by the metal or metals used in minor proportion. In this way copper gives a reddish color and palladium a whiten color. Basically, one Karat is divided in 24 parts or 1000 fractions. Then the precision or exactitude of this unit is 1/24 or 1/1000. The following table shows a summary of the main marketable gold alloys.

It was mentioned that gold alloys adopt different colors, which are influenced on the type of metal(s) to be added. The next table shows some gold alloys employed in jewelry.