2. bite with your teeth. You can bite gold, and vice versa.
3. Use nitric acid to distinguish the authenticity of gold, and put jewelry in nitric acid. If it is gold, it will be safe and sound, and there will be no change. If it is copper, it will emit green smoke.
4. Listen to the composition of the sound and naturally attach jewelry from a height. If it just makes a "beep" sound, and it has no rhythm and elasticity, it is gold with a purity of 990‰. If the sound is long and elastic, it means that its color is not high, and the jewelry contains more metal components such as copper.
5, taste the authenticity, put the gold ornaments in your mouth and lick them with your tongue for a while, then smoke, if there is no smell, it is gold; If it smells like sweet silk, it means copper.
Extended data:
Most of the copper in nature exists in the form of compounds, that is, copper ores. The activity of copper is weak, and the reaction between iron and copper sulfate can replace copper. Copper is insoluble in non-oxidizing acids.
Because 24k pure gold is soft, when making jewelry, gold is often alloyed to change its hardness, ductility, melting point, color and other characteristics. In the alloys of 22k, 18k, 14k or 10k, there will be high-content copper, silver, palladium or other base metals. Copper is the most commonly used base metal, which will make the alloy red.
Hundreds of years ago, there was 18k gold in Russian jewelry-rose gold with copper content of 25% cast in copper mold. 14k gold-copper alloy is similar in color to some bronze alloys and can be used as badges. ?
Blue gold is an alloy made of gold and iron, but it is difficult to be used in jewelry making because of its fragility. Zijin is an alloy of gold and aluminum, which is usually only used for specialized jewelry. 14k or 18k gold and silver are green and yellow after alloying, so it is called green gold. The alloy of gold with palladium or nickel can form platinum alloy. The white 18k gold alloy is silver and contains 17.3% nickel, 5.5% zinc and 2.2% copper.
Baidu encyclopedia-copper
Baidu encyclopedia-Jin