◆ What are the simple ways to identify the authenticity of gold?

Among the most common gold in society, raw gold has placer gold; There is pure gold in cooked gold; Among the clear colored gold, all kinds of gold ornaments, gold bars and gold utensils are the main ones. The general method to identify the authenticity of these gold is to shrink them with nitric acid. If there is no reaction, most of them are gold, but there are also platinum (platinum) and a few rare and precious metals that are not afraid of nitric acid, but people do not often encounter such metals.

There are many adulteration methods of placer gold, mainly including:

(1) gold-plated brass, placer gold mixed with copper powder and pyrite;

(2) silver-plated placer gold mixed with silver powder;

(3) placer gold is added at the end of the furnace.

● Generally, the first kind of adulterated placer gold can be preliminarily judged whether it is fake or not as long as it is burned with fast fire. If there are many black objects, it is adulteration. If placer gold is completely unchanged, it is real placer gold; Or use sand acid to remove some of its grinding marks. If the wear marks change or disappear, it is fake placer gold.

In the second kind of fake placer gold, because silver is not easy to be discolored by fire, it can be used to cut open the placer gold ball and see whether there are white spots on the cross section under a magnifying glass. If there is, it is fake placer gold; Or use the grinding path of nitric acid point again. If there are white spots, it is mixed with silver placer gold.

● The third placer gold is the most deceptive, because the ash in the furnace is not afraid of burning or acid. At this time, it is best to grind the first part with aqua regia (a mixture of hydrochloric acid and nitric acid of 3: 1). If the wear marks disappear, it is real placer gold. If there are obvious traces, it is that fake placer gold is mixed at the bottom of the stove.

● There is a formula to identify the clear gold in cooked gold, that is, weighing, looking at color, judging rhyme, folding soft and hard, and using acid points. Because the density of gold is obviously higher than common metals such as copper, silver, lead and zinc, it is about twice as heavy as silver and copper with the same volume. If the object is gold and feels heavy, it is a "golden pendant" of the human system, and vice versa.

● Gold has its unique golden luster (except those with low fineness). Pure gold will shine brilliantly in strong light, which other metals, including copper, do not have.

● Gold with high fineness has no charm and elasticity when thrown on the ground, while gold with low fineness has slightly brighter sound quality, and copper products are thrown loudly on the ground. Therefore, according to the sound of knocking objects, it can help us distinguish ordinary metals from gold.

● Gold is characterized by good ductility and low hardness. Pure gold is soft, but copper bars are hard to break. Or use a pin (nails will do) to draw, the strength is not big, and the traces are obvious, but the copper is slightly larger and the traces are slightly worse. Soft folding and hard folding are only applicable to rings, gold wires and the like, and gold bars, gold coins and gold bricks are more difficult. It is also very effective to judge the authenticity of gold with a grinding head, but it is necessary to polish the inspected object in different directions. If the colors of several grinding channels are obviously different, there is no doubt that they are adulterated.

● If you don't believe in the above methods of identifying ripe gold, you can only use nitric acid, that is, use nitric acid to spot its wear marks to judge its authenticity.

◆ Identification of gold jewelry

1. The genuine product is soft when it is bent by hand, and it is easy to bend continuously. It is easy to straighten when pulling by hand, and there will be traces when scraping with hard objects.

When the gold ornaments are thrown on the floor, they will make a plop sound. The falsetto is sharp and bright, and it jumps higher than real gold.

3. The true color is dark yellow, excessive dividends are fake gold, and light colors are mixed gold such as silver and aluminum.

4. It's really heavy, but it's fake.

True fire does not change color, and false fire does not resist fire, but becomes dark purple and dull.

6. When it really burns red, it is quenched into water and its color remains unchanged.

◆ Identification of Jade Jewelry

● First of all, pay attention to the gold content. In China, it is marked with the words "foot red, pure gold, 80%, 70%, 90% and 100%". Internationally, the gold content is expressed by "K", 24K is pure gold, with a content of about 99.6%, 22K is 9 1.3%, 20K is 83%, and 18K is 75%, 65438.

● Identification of jade ornaments: Real jade is very hard and wear-resistant. If there are cracks inside the jade, the quality is poor. For example, fake jade with wrinkles on the surface and bubbles inside is light in weight and low in hardness, and the sound is crisp when knocking each other.

◆ Identification of rare gold jewelry

Rare gold jewelry is an alloy made of copper as the main raw material and adding trace elements appropriately. It does not contain gold, and its appearance is 14-24K gold. Its wear resistance is better than gold, and its specific gravity is lighter than gold. C20K, C 18K and C 14K are equivalent to 20K, 65438+.

◆ Archimedes judges whether gold is true or false.

King Ashero of Syracuse gave the goldsmith a piece of gold as a crown. After the crown was made, the king felt a little light in his hand. He suspected that the goldsmith was adulterated, but the goldsmith swore with his head that he didn't, and weighed it to his face. The result is as heavy as the original gold nugget. The king still had some doubts, but he couldn't produce any evidence, so he called Archimedes and asked him to solve the problem.

After returning home, Archimedes closed the door, thanked the guests, thought hard, but was puzzled.

One day, his wife forced him to take a bath. The water overflowed when he jumped into the swimming pool. Archimedes heard the sound of running water and his inspiration came out at once. He jumped out of the pool and rushed into the street naked, shouting, "you guy!" Yulega! (meaning discovery) ". The lady was really anxious this time, muttering "really crazy, really crazy" and then chasing out. People in the street don't know what happened, so they all follow them.

It turns out that Archimedes found a solution to the crown problem by overflowing the bathtub: the same substance with the same quality is soaked in water, and the spilled water should have the same volume. If you put the crown in water, the volume of the overflowing water should be the same as that of the gold nugget with the same mass, otherwise the crown must be adulterated.

After Akivid ran to the palace, he immediately found a basin of water, a piece of gold and a piece of silver with the same weight, and soaked them twice. The overflow of silver was almost twice as much as that of gold, and then he soaked the crown and gold nuggets in pots respectively. The crown overflowed more water than gold. Obviously, the quality of the crown is not equal to the quality of the gold nugget. The crown must be adulterated. In the face of the iron fact, the goldsmith had to bow his head and admit that the crown was indeed mixed with silver. The annoying mystery of the crown was finally solved.