18k gold is an alloy with a gold content of at least 75%, that is, an alloy with a gold content of 18/24, and the remaining 25% is other precious metals, including platinum, nickel, silver and palladium. The gold seal of 18K is generally AU750, 18K or G750.

The calculation method of K gold is to divide pure gold into 24 parts, and 24k gold is pure gold, but in reality, it is impossible to have 100% gold, so China stipulates that gold with a content of more than 99.6% can be called 24K gold.

Extended data:

There are four "C" principles in selecting diamonds: cut, color, clarity and carat weight. This is the key to identify the quality and value of diamonds.

incision

Cutting is the only human factor. A skilled diamond cutter can make a good diamond shine, and he can make the internal light reflect to the surface of the diamond to the greatest extent. The cutter must cut symmetrically, just like looking in the mirror.

colour and lustre

In some big jewelry stores, some diamonds are displayed for comparison. They arrange diamonds of various color grades in a row to help customers compare, because ordinary customers can't tell the color of diamonds with the naked eye. The color of diamonds is colorless as the top grade, and gradually comes second with the deepening of yellow.

pure

Generally speaking, defects determine the value of diamonds. More precisely, it depends on the impurity content in the drilled ore. Almost every diamond contains impurities, even the best quality diamond will have some defects. When its cleanliness is LC level, it can be regarded as flawless level.

carat

Carat was once considered as the decisive criterion to measure the value of diamonds. When someone says that he bought a 2-carat diamond, people will find it unbelievable. In fact, the cut, color, purity and weight of a diamond are equally important to its value.

Baidu Encyclopedia-18K

Baidu encyclopedia-diamond ring