China Nonferrous Metals News

1. Discrimination of texture

Gold and silver, with their unique material beauty, are regarded as treasures and become symbols of wealth. It has always been made into exquisite utensils and ornaments by Royal dignitaries. Because of its special material and stable physical and chemical properties, gold and silver wares can be processed and renovated. For this reason, there are not many gold and silver wares handed down in ancient China, mainly from archaeological discoveries, which are mainly from hoards and Buddhist underground palaces. According to incomplete statistics, more than 10, 000 pieces of gold and silver ware have been unearthed all over the country. These unearthed gold and silver wares are large in number, various in variety and of definite age, which provide reliable basis for the collection and study of ancient gold and silver wares, and some become the standard tools for identifying gold and silver articles. So, how to collect and identify gold and silver wares? It is mainly the identification of material texture. Compared with other cultural relics, the material quality of gold and silver wares is of high economic value. Some counterfeiters make huge profits by using copper, imitation gold materials such as thin gold, deposit, and gilded, gold-plated or gold-plated materials. For a long time, people's understanding and identification of gold and silver texture have formed a set of experience and methods. We can start from their physical and chemical properties respectively.

■ Identification from physical properties

(1) First of all. This method should be said to be the oldest and most direct method. Because gold and silver wares show different colors according to the content of gold, which is what we usually call the fineness of gold. There is a pithy formula of "seven green, eight yellow, nine purple and ten red" in folk circulation. The ancients thought that the color of pure gold should be yellow, but it was slightly cold red when looked at carefully. Therefore, "red gold" was used to express full gold. But pure gold and silver in absolute sense does not exist. Since the modern advanced metallurgical technology is adopted, the purity of gold can only reach 99.95% - 99.99%. Therefore, when we distinguish gold and silver wares, we should first look at its quality. If it is pure gold, the color should be yellow. If the color is not correct or there are impurities in the middle, there must be something wrong. For example, some counterfeiters add other metals into gold, which will definitely affect the luster. Generally speaking, the more impurities added, the lighter the color of gold. Experienced experts can roughly determine the content of gold as long as they see the composition of the gold. In addition, it is necessary to have long-term training, observe more and accumulate more experience to achieve this step.

Of course, from its color identification, is only the first step, is a relatively rough way. To further identify gold and silver, but also from other aspects, the following will introduce another method.

(2) Listening is also the key link. If we have made great efforts to see this point, we may as well listen to it and see what it tells us. Generally speaking, the density of gold is relatively high in metals, and its proportion is 19.3. As long as you take it in your hand, you will feel heavy, which is what we usually call pressing hands. Because of the special physical properties of gold, when it falls on a hard board, it will make a dull sound, while that of iron and copper will make a relatively clear sound when it falls to the ground. The real gold falls one meter above the ground naturally, with no more than three jumps on the ground, while the counterfeit one will.

(3) Pay attention to "pulling". When we look at things, we usually have to see the essence through their phenomena. The same is true of gold and silver. The "pull" is also an important method. We all know that gold has good ductility. 1 gram of gold can be drawn into a gold wire with a diameter of 0.00434mm and a length of 3500 meters; it can be hammered into a gold foil with a thickness of only 0.23nm. The higher the purity of gold, the softer the texture. Therefore, gold products are generally easy to break and not easy to break. If you bite with your teeth, you will leave marks on the gold surface. With an ordinary pin, the mark can be easily drawn. A gold object is in the hand. If it is in a weak or small place, you can feel the soft texture by gently pulling it with your finger.

If other impurities are added to gold, there is no such property. For example, the addition of aluminum or iron, silver and the like, either become brittle and brittle, or the color has a big change.

■ Chemical identification

(1) Fire

As the saying goes, "true gold is not afraid of fire". Pure gold is burned red in the fire and its color remains unchanged after being taken out. According to the chemical property of gold is stable and not easy to be oxidized, the test can be carried out. If the color changes after removal, it must be caused by impurities.

(2) Acid drop

According to the corrosion resistance of gold, it is identified by chemical test. Gold has strong chemical stability. Nitric acid, hydrochloric acid and sulfuric acid do not react with it. It can only dissolve in aqua regia (mixture of hydrochloric acid and nitric acid 3:1). Generally, nitric acid is used as reagent for gold test. First dip a little nitric acid on the glass rod, and then gently drop it on the utensil. If the color does not change, it is gold.

We can also use the touchstone test. Most of the gold shops in ancient China used this method. Now most banks and gold shops in the United States use the touchstone, and they are equipped with a set of standard reference plates with known gold content.

The above method of burning and acid dropping is the most effective method to identify gold and silver wares with high accuracy, but it is also destructive. No one would venture to use this method for an exquisite device that looks like a genuine one. Therefore, the focus of distinguishing gold and silver wares should be on the identification of their physical properties. Fortunately, the gold and silver wares are naturally beautiful, so it is easier to identify the authenticity. It takes a lot of effort for counterfeiters to counterfeit them. In addition, if conditions permit, modern high-tech means can be used, such as X-ray fluorescence analysis, chemical spectrum qualitative analysis, etc. Scientific and technological means have high detection accuracy and can know the quality of gold and silver.

2. Distinguishing the age from the false

Different from other cultural relics, such as coins and pottery, gold and silver wares have obvious age marks when they are unearthed. It is difficult to determine the age of gold and silver wares. For example, judging from the name, there are few inscriptions on gold and silver wares before the Tang Dynasty. However, after the song and Yuan Dynasties, inscriptions on gold and silver articles have become very popular. If there are no inscriptions on the gold and silver wares unearthed at the same time, it is possible to do so According to the inscriptions, we can roughly infer the age of the objects.

In fact, as long as we carefully grasp, we can still find traces of history on each piece of gold and silver.

The earliest gold products of Shang Dynasty have a history of more than 3000 years. The distribution of the Shang Dynasty's gold wares was mainly in the Central Plains with the Shang culture as the center, and the minority areas in the north, northwest and southwest of the Shang Dynasty. Generally speaking, the shape and technology of this period's gold ware are relatively simple, the shape is small, the ornaments are rare, and most of them are ornaments.

The characteristics of regional culture in this period were very distinct. Most of the gold products in the Shang Dynasty were gold foil, gold leaf and gold sheet, which were mainly used for ornamentation. For example, gold wares unearthed from Sanxingdui site.

During the spring and Autumn period and the Warring States period, gold and silver wares were fresh and lively. During this period, the production of gold and silver ware had a great improvement, mainly in detail, and its decorative effect was more brilliant. In particular, the emergence of a large number of gold and silver inlays almost became a symbol of the high level of Technological Development in this period. The development of bronze line engraving technology also had a significant impact on the development of gold and silver technology.

During the Han Dynasty, the quantity and variety of gold and silver products increased, and the craft became mature. Basically, it had separated from bronze craft and embarked on the road of independent development. However, most of the gold and silver products were still ornaments, and the gold and silver vessels were relatively rare and did not have a great development until the Tang Dynasty.

In the Tang Dynasty, the development of China's gold and silver ware was at its peak. During this period, not only the number of gold and silver wares increased sharply, but also the varieties were rich and colorful. Great changes have taken place in the style of its utensils and patterns. The Tang Dynasty absorbed foreign culture and integrated into the national culture, and finally formed an independent national style.

After the Tang Dynasty, the development of China's gold and silver wares tended to be conservative on the whole, lacking the vitality of the Tang Dynasty's gold and silver wares.

However, gold and silver products once again showed a trend of combining with other artifacts, and a large number of decorative and matching products appeared, which involved a wide range of fields, unprecedented.

After mastering the main characteristics of the gold and silver wares of different ages, it is very important to distinguish the fake.