Gold is the only metal on Earth that has a beautiful bright yellow color in its pure form without additives. Natural gold has a good gloss, which is greatly enhanced by polishing. Usually, gold is obtained during the development of natural deposits or incidentally during the extraction of other metals from ores. Native natural gold is usually not pure, copper and silver are present as main impurities, and many other elements are found as additional impurities. Therefore, in order to clean it, gold is subjected to special processing (refining) at gold mining enterprises.
Refined gold is already produced in 99.99% purity in the form of ingots, wire, foil, strips, ribbons and other semi-finished products. In this form, it is a very soft and ductile metal, for example, one gram of such metal can be used to draw a wire three and a half kilometers long. In the jewelry industry, gold is already used in the form of various alloys to make jewelry. All these alloys have a certain gold content and in accordance with this they are assigned samples. The lowest precious metal content has 375 gold samples.
The alloys of this sample contain only 37.5% of pure gold, the remaining components are copper and silver. Jewelry industry experts sometimes even call it a gold-containing alloy of copper and silver. According to Russian standards, 5 alloys are provided for which 375 gold samples are applied. All these alloys usually fade in the surrounding atmosphere, so this property greatly limits their scope. The whole gamut of colors of these alloys is in the range from yellow to red, however, it most often coincides mainly with sample alloy 585 of the so-called "samovar" red gold. Alloys having a pink color are the most durable and hardest, they lend themselves well to soldering.
Despite the fact that it is low-grade gold, it is used in the jewelry industry. Typically, these alloys are used in the manufacture of wedding rings. In the Russian Federation, according to the standard, there are no alloys of a lower sample, but in European countries 333 gold is used, which is also used for the manufacture of jewelry and jewelry. Gold alloys of various compositions are widely used in the jewelry industry, since when you add various ligatures to them, you can get different colors: red, pink, green and even white, as well as a large range of intermediate shades.
Often, alloys consisting of many components are used to produce jewelry. If a 375 gold sample is obtained mainly by adding copper and silver to the alloy, then in the remaining samples, palladium, platinum, zinc, cadmium and nickel are also used as a ligature. Each component is able to endow the alloy with various properties. Silver makes gold alloy more malleable and ductile and lighter. The addition of copper increases the hardness of the alloy, but its corrosion resistance deteriorates. Also, such an alloy gets a brighter red tint.
The addition of cadmium makes the alloy fusible and is often used as a gold-containing solder. Zinc also gives the same properties, in addition, it brightens the alloy, which makes it possible to use it in the manufacture of white gold. Such expensive metals as platinum and palladium give plastic alloys plasticity, elasticity and significantly brighten them. In addition, they give them high anti-corrosion properties. However, a 375 gold sample is not made with the addition of these metals. The main components for it are gold, silver and copper.