What are the colors of gold and how to change the color of gold?

What are the colors of gold and how to change the color of gold

The original gold color is yellow, as already mentioned in the subject Chemical Composition of gold that gold exchange pure metal soft and easy ways and this is what he can from forming in the manufacture of jewelry and ornaments also enter into complex electronic industries
But gold is mixed with other metals such as copper, silver, platinum and nickel to increase rigidity to the extent required and can change its color to increase the proportion of minerals added to him and for the manufacture multiple forms and colors of jewelry and ornaments
Gold can be obtained by adding copper to red and whenever Madt proportion copper ذاد color red
And can be obtained by adding white gold or silver for gold and nickel gold White Bihtoa on the 20% of nickel and 5% of silver
The gold blue can be obtained by adding a small percentage of iron
As for gold, purple can be obtained by adding the percentage of aluminum
Green gold can be obtained by adding 25% Silver
Note whenever Madt the percentage of copper in gold  color Cro more Madt the ratio of nickel or silver color white and according to the 
following Hram