How do you transform gold, which is yellow in nature, into a black metal? This is how black gold is obtained and how to clean it ♦︎
Gold in nature is yellow. But for some time now, jewelry has also loved to use gold with different colors. The main ones, in addition to the natural color, are the rose gold and white gold alloy. But that’s not all: there are many colors of gold, which depend on the metals with which it is melted. One of the main ones is the black, or blackened color.
Also read: The 9 colors of gold
Among the colors used for gold there is also black. It is almost a paradox, because gold, unlike silver or iron, does not oxidize in contact with air. But the idea of wearing black gold appeals to many women and to many designers who make jewelry with this dark shade of metal.
But not all black gold is the equal. To transform yellow gold into dark metal there are several methods. This also means a different duration or strength of the gold color.
The first way is to create a patina by applying compounds containing sulfur and oxygen or ruthenium.
Another system is to proceed with a chemical deposition with steam: it is obtained with the use of amorphous plasma and carbon. Finally, gold can be induced by artificial oxidation with an alloy of cobalt or chromium, usually at 25%. At this point this alloy is brought to a high temperature until a black black oxide layer is formed.
High tech method
The same effect is obtained by combining gold in alloy with copper, iron or titanium or with a mix of three different metals, for example 75% gold, 15% cobalt, 10% chrome. However, by changing metal, the dark shade of gold can tend to brown or green.
On the other hand, there is an ultra-technological treatment, which involves the creation of nanostructures on the surface, but it is rarer. This is how it is obtained: a laser pulse hits the gold for the duration of 1 millionth of a billionth of a second. A minimal duration, which however deforms the surface of the metal creating an area that absorbs practically all the light, which thus appears as black. But it is a system hardly used in jewelry.
How to clean the black gold
Cleaning a jewel in black gold is simple: just immerse it in a bowl with a little warm water and a few drops of liquid soap. After about ten minutes, the jewel can be cleaned with the help of a soft-bristled toothbrush. Rub carefully, especially if gold is plated: the surface may be damaged. Finally, rinse. It’s better to avoid stress on jewels with particularly delicate stones, such as the opal, or pearls.