Not just yellow, white and pink. All colors of gold
How many are the gold colors? The most common answer to this question is three: yellow gold, white gold and rose gold, the most common in jewelry. Actually, there are nine of them, although some of these are little used, and include shades ranging from red to green, from purple to blue, to black. In its natural state, gold is yellow: the other colors (with the exception of black, which requires other treatments) are obtained by combining gold with other metals.
How is the purity of gold measured?
The gold used in jewelery is always a metal alloy: thegold pure, in fact, is too soft and cannot be worked to create jewelry. The purity of gold is measured in Carat, which indicate the amount of pure gold present in the alloy: 100% gold is 24 carats and is used for ingots, while 22 carats (91,7%) is used to mint coins. The most common gold for jewelery is 18-karat (75%), but 14-karat (58,3%) is also used. The minimum number of carats in jewels on the market varies according to the country: in Italy it is 8 carats (33%), while for example in the United States gold is defined as such if it has at least 10 carats (41,7%)
Therefore, 18-karat gold is made up of 3 quarters of pure gold and 1 quarter of another metal, or a composition of several metals in different percentages. It is these metals that give gold its different shades. So let's see how all the are obtained gold colors at 18 carats.
The 9 colors of gold
The classic colors
Yellow gold
It is the color closest to that of natural gold and is the most traditional and loved for precious items. Yellow gold consists of 75% gold, combined with silver (7-12%) and copper (13-18%): the percentage of these two metals depends on the intensity of the yellow to be obtained. Indeed, by increasing the amount of silver, the color of the gold will be lighter.
White gold
In second place among the gold colors more common in jewellery, there is white gold, obtained with a 25% of nickel, silver or palladium. The nickel alloy is more resistant, while the palladium alloy makes it more malleable. To increase the shine of white gold jewels it is often used to subject them to a treatment rhodium plating.
Rose gold
Very popular in 20th-century Russia, rose gold had since disappeared from modern jewelry, but it has been back in fashion for several years. It is obtained by combining XNUMX% of yellow gold copper and 5% of silver.
The unusual
Red gold
It is used less than rose gold, but the composition is similar: the percentage changes copper, which rises to 25% and therefore gives a more intense colour.
Green Oro
An apparently unusual colour, but already known in antiquity: in fact, to obtain green, it is enough to link pure gold withsilver and copper, in the same amount (12,5% each). By changing the percentages of silver and copper and adding a small amount of cadmium the shade of green becomes more intense.
Purple Gold
Also called amethyst gold, it is an alloy of gold and aluminum. However, purple gold is not often used to create jewelry because, due to the smelting and metalworking process, it is much more fragile than other types of gold.
Dark and intriguing: the new colors of gold
Blue Gold
From the union of gold and iron blue gold was born: the nuance derives from a heat treatment which oxidizes the iron atoms on the surface of the gold. Blue gold can also be obtained from an alloy with two rare metals, the gallium andIndian. Again, this is a brittle material.
Gray gold
It is obtained by combining gold and palladium, or silver, with the addition of manganese, which gives the metal the gray hue, much appreciated in contemporary jewellery.
Black gold
It is the only one among the gold colors, which is not obtained from an alloy with other metals, but from chemical treatments: the surface of the gold, in fact, is darkened with a galvanic bath which uses ruthenium, chromium or cobalt. More recently, the same result has been achieved through the creation, thanks to 3D and laser technologies, of metallic nanostructures that are fixed on gold.