1, fire attack mode:
Fire knows the truth. "Real gold is not afraid of fire." If the jewelry is still yellow and does not deform after being cooled by high temperature fire, it is gold. This is the saying that "fire sees real gold"; If it turns black, it is not real gold, but a counterfeit made of other metals.
2, "water" attack method:
That is, nitric acid is used to distinguish the authenticity of gold. Put the 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.
In addition, some traditional older gold jewelry is not very pure, with a little silver and even a little copper (sometimes the surface is a little green). You can put it in nitric acid diluted with water 1 time, heat it for half an hour, take it out and rinse it with water. At this time, the silver and copper on its surface have been removed.
If you add some salt (sodium chloride) to the nitric acid just now, if there is white precipitate (silver chloride) immediately, it means that there is silver in the jewelry. Please rest assured that this treatment will not damage your gold jewelry, on the contrary, it will make the color of the jewelry more beautiful.
Second, the eye view method
1, recognize the manufacturer and color:
The surface of gold jewelry should be printed with the manufacturer and alloy purity (fineness), and the words should be clear. If there is no mark on the jewelry, or the mark is vague, it is necessary to doubt the authenticity of the gold jewelry.
2, check the color and change:
Gold should be bright red and yellow, and its luster and color are lasting. The higher the fineness, the more beautiful the color, so people often say "seven green, eight yellow, nine five red". Other so-called gold ornaments lied by polymetallic can be identified by color.
Third, the auditory method.
Listen to the voice and say the composition. If jewelry is naturally attached from a height, if it only makes a "beep" sound, and it has no rhyme 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.
Fourth, the manual weighing method.
That is, compare the weights manually. The specific gravity of gold is 19.3, which is higher than that of silver, copper, aluminum, tin and other metals. The same volume of gold is 40% heavier than silver, 1.2 times heavier than copper and 6. 1 times heavier than aluminum.
By weight comparison, we can also identify whether there are other metals as fake gold ornaments. The easiest way is to weigh yourself by hand, and then you can know the truth. As the saying goes, gold is very heavy, because the same volume of gold is much heavier than other metals such as copper and aluminum.
Step 5 grind your teeth
Teeth biting Jian Zhen king. Gold has low hardness and is relatively soft. Bite lightly with your teeth, and there will be traces. Other metals do not have this characteristic. Moreover, the higher the fineness of gold jewelry, the softer it is, and the fineness can be checked by bending.
If the color is low and contains more silver and copper, it is not easy to bend. This method can be used to identify whether gold ornaments are shoddy or not.
Extended data:
The simple substance (free form) of gold, commonly known as gold, is a popular precious metal, which has been used as currency, preservation and jewelry for many centuries. In nature, gold exists in the form of simple substance in gold nuggets or rocks, underground veins and alluvium.
Gold is also one of the currency metals. Gold, a simple substance, is solid at room temperature, with high density, softness, brightness, corrosion resistance and the highest ductility among known metals.
Copper is a transition element with chemical symbol Cu and atomic number 29. Pure copper is a kind of soft metal. When it is just cut, its surface is reddish-orange with metallic luster, and its simple substance is purplish red.
Good ductility, high thermal conductivity and electrical conductivity, so it is the most commonly used material in cables, electrical and electronic components, and can also be used as building materials to form a variety of alloys. Copper alloys have excellent mechanical properties and low resistivity, among which bronze and brass are the most important. In addition, copper is also a durable metal, which can be recycled many times without damaging its mechanical properties.
References:
Gold (one of the metal elements) _ Baidu Encyclopedia Copper (metal element) _ Baidu Encyclopedia