Knowledge expansion:

18k indicates that the purity of gold in jewelry is 18K. 18K is not weight, but proportion. Theoretically, the gold content of 100% is 24K.

In fact, gold with a purity of 100% is impossible. Our country stipulates that gold with a purity of over 99.9% is 24K. 18K means that the proportion of gold is 18, 18/24=0.75, that is, 750 thousandths. Therefore, the gold of 18K is marked with the words AU750, 18K or G750.

75% of the precious metals in 18K are gold and 25% are other metals. As we know, pure gold is very soft, and it is not suitable for jewelry modeling and setting gems. 18K gold with other metals not only has the same valuable value as gold, but also has perfect composition ratio.

It has the advantages of strong ductility, high hardness and changeable color. When used in jewelry design, it is not only colorful, but also firm in structure, which can give full play to complex and exquisite creative expression and realize various shapes. Therefore, 18K gold is widely used in contemporary jewelry and is very popular.

18K precious metal contains 25% other metals, so it can be made into white, yellow, rose red and other different colors, which are called white 18K gold, yellow 18K gold, red (rose) 18K gold, black 18K gold and so on.

Gold is a simple form of chemical element gold (Au), which is a soft, golden yellow and corrosion-resistant precious metal. Gold is a rarer, more precious and more valuable metal.

Generally speaking, gold in the world is measured in ounces. In ancient China, gold was measured in ounces, which was a very important metal. It is not only a special currency for reserve and investment, but also an important material for jewelry industry, electronics industry, modern communication and aerospace industry.

The chemical symbol of gold is Au, and the financial English code is XAU or gold. The name Au comes from a story of Aurora, the goddess of dawn in Roman mythology, which means shining dawn.