How to identify ancient jade

There are several steps in identification: patina, erosion, jade, form and spirit, corrosion, decoration and knife marks. You can tell whether there are hands at a glance, only roughly. The appraisal is very strict. Without microvision, there would be no case. [So learn to identify with a magnifying glass]

A, ancient jade patina is an oxide film, which can be divided into soft patina and hard patina. Soft patina feels astringent when held in your hand (meat head in northern language), while hard patina feels bright glass. Soft and hard patina can be transformed into each other under certain conditions. Long-term playing with hands or soaking in liquid medicine can make the imitation patina. Experienced people can tell. Natural sapwood also has patina, which is generally high in hardness.

B, erosion can be divided into internal erosion and external erosion. Internal corrosion is a brittle and white flocculent crystal produced under certain conditions. External ooze is the invasion of external media. The internal ooze develops from the inside out, while the external ooze develops from the outside in, promoting each other until calcification. The ancient jade with the outer Qin Dynasty in Yuan Dynasty is of good quality and may not be suitable for the inspection of the inner Qin Dynasty. The erosion status is related to the density distribution of jade, the brittleness of crystal and the nature of external medium. The imitation oozes and floats, which is really heavy. Qin Gui can't tell the truth, eg an old fool's new palace.

C, jade:

Hetian jade in Xinjiang: it is the most beautiful jade and the jade with the largest cultural carrying capacity. After the Shang Dynasty, this jade was chosen by the nobles. Its molecular structure is consistent with today's Russian jade, and Russian artifacts can't tell whether it is Hetian jade or Russian jade. Russia is rich in mountain materials and Hotan seed materials. Hetian jade in the Western Han Dynasty has the most complete variety and the best quality, such as topaz and suet jade. Liaoning Cave Jade: This kind of jade is widely used in Hongshan Culture. Ancient jade is rich in materials and fine in workmanship. [Note the difference between topaz and topaz]

Dushan jade, Henan: There are two main colors, white cyan and white green. White cyan is mostly used as an antique device, and white green is mostly used to resist imitation jade. This kind of jade is rare in ancient vessels.

Earth jade: Earth jade with various attributes, mostly stone and semi-jade. Common in ancient artifacts, there are Zhuge Liang's artifacts, funerary objects and so on.

Afghanistan jade: Low density and high hardness, much like glass. This kind of jade is rare in ancient vessels.

Glass feeder: A large number of feeder ornaments [many Warring States] have been unearthed. This is a joke. Now the feeder is made like jade, and many experts punch holes. [The general hardness test method must be deleted in the identification of ancient jade. Ancient jade has patina and cannot be destroyed. ]

D. Form and spirit:

If God is the soul of art, then the soul of the ancients must be different from that of the present. Therefore, no matter how good a craftsman is, he can't imitate the souls of the ancients. This soul must be understood from the real thing, not self-righteous.

E. corrosion:

Some media have corrosive effect on jade surface. The corrosion traces of jade articles in the soil are mostly dotted, like the stars in the sky or the concentration of stars; Rath than a continuous sheet. Iron sulfate and iron sulfite formed after iron decay in Han tombs have the greatest corrosion effect on jade.

F, decoration:

Literary ornaments are ever-changing and easy to imitate, and should not be used as a basis for judging authenticity. Knowledge of cultural relics contributes to dating.

G, knife marks:

The study of knife marks plays an important role in the identification of ancient jade. First of all, we should master some mechanical knowledge, such as shaft, sleeve, speed, coaxiality, jumping, deflection, structural characteristics, and the difference between electric and non-electric tools. The evolution of lifts and so on.

Brief Introduction to the Evolution of Coaxiality of (1) Tuo Machine Tool; Error between the center of Tuo disk and the center of rotating shaft. Jumping is the up-and-down displacement of the tray every turn. Deflection is the error that the tray deviates from its plane every turn. Now there is an error in the machine ring, and the error in the ancient machine ring is even greater. Theoretically speaking, Tuoju should appear before jade. Without Tuoju, there would be no jade. Since the appearance of machines, difficult jade processing has become possible. The shaft rotates in the shaft sleeve, which is the support of the shaft, and the shaft and the shaft sleeve rub. Rotation: It was manual in ancient times, but now it is electric. The difference between slow speed and fast speed is hundreds of times. The unearthed tubular and columnar jade articles are probably shafts and bushings. Before Shang Dynasty, the shafts and bushings were mostly jade articles, during Shang and Zhou Dynasties, they were mostly bronzes, and after Han Dynasty, they were mostly forged iron. Therefore, the accuracy of camel machines and tools in Han dynasty was greatly improved, and the processing capacity was obviously enhanced. This is not only manifested in the cooperation between shaft and sleeve, but also in the machinability of parts and the structural accuracy of machine ring. Machine ring varieties and so on. It is not surprising that exquisite high relief appeared in Han Dynasty, which is an epoch-making alum in China jade history. During the Tang and Song Dynasties, the structure, precision and types of tuoji were more perfect, but there were few breakthroughs. It was not until the Qing Dynasty that Tuo's precision machines and tools made new progress. Modern electric tractors have high precision, high speed, harder knives, large feed force and strong cutting power, so the knife marks are often rough and stubble-clearing. Because modern lifts are exquisite and flexible, there are also many fine products. The cost of this imitation will be high, and it is impossible to copy everything in place. No imitation is in place, only research is not in place.

(2) The different performance of the tool mark identification machine ring will inevitably lead to different handicraft methods and different tool mark characteristics. If you master it, you will master the weapon of ancient jade identification. This is also the shortcoming of traditional ancient jade appraisal theory, that is, the lack of knife mark research theory. Before the Warring States period, Tuo's machines and tools were similar, and generally only rough machining could be carried out. The details are all processed by hand tools. At that time, hand tools could only draw a white mark with one knife, and a part cost tens of millions of dollars. It can be seen that the time difference and manpower input are as fine as hair, and the scrutiny is also done with multiple knives. This process is natural, meticulous and neat. It's just that the tombs are rough, and the holes and sides are not finished. In the Han Dynasty, artifacts were intertwined with hand-made knife marks, which greatly improved the ability of handicrafts. After the Tang dynasty, the artifacts were mainly tuo marks, and it can still be seen that with the progress of tuo tools, the traces on the surface of artifacts have changed. [Ancient jade, even if polished, is not enough to destroy the surface knife marks. ] stubble collapse and thick knife marks are all caused by current power tools. Wudao is modern polishing, and imitation chrysanthemum is chemical polishing. There are obvious tool marks on the inner wall of the borehole, which are caused by the electric drill. The difference between drag marks and electric tool marks can only be mastered gradually in practice.