1. Because the texture of glass is very brittle and hard, the structure is clearly arranged, and it lacks the density and toughness of jade, so it can't stand strong and high-speed rotary carving, so it is generally impossible to process high relief and round carving on glass.
Second, use a magnifying glass to find bubbles, even if you can only see one, you can confirm that it is not jade.
Thirdly, chromium oxide is added into the glass, and the color is close to ruby; Adding cobalt oxide, the color is close to sapphire; Adding chromium oxide and copper oxide, the color is close to emerald ... and so on, there are many kinds of fake jade. However, their colors are always relatively thin, lacking the oily and rich feeling of natural jade color.
The identification of new jade and old jade is different. The identification of new jade focuses on the authenticity of the variety, the quality of the texture and the fineness of the sculptor. The identification of old jade is relatively complicated. In addition to several basic requirements, new jade also needs to identify its production and historical value.
Appraisal of ancient jade
Textual research, identification and judgment are made on the texture, age, name, function, grade and authenticity of jade unearthed cultural relics and handed down cultural relics.
The identification of jade texture depends on visual inspection, mineralogy and gemmology to determine the mineral types, chemical composition, crystal structure and physical characteristics of various jade. Usually, hardness, specific gravity and refractive index can be measured without destroying the original. If the ancient jade is damaged, a small amount of approximate nondestructive sampling analysis is allowed. With the help of infrared spectrum, X-ray powder crystal and scanning electron microscope, we can observe the optical properties and structure of the identified jade and determine its crystal system. According to the general concepts of gemmology and mineralogy in the world, jadeite only includes jadeite of alkaline clinopyroxene and nephrite of calcium amphibole, both of which are chain silicate minerals and are generally called true jade. If it does not belong to the above range, it is fake jade or semi-jade. The real jade in ancient China was nephrite. Eight jades were unearthed at the Chahai site in Fuxin, Liaoning Province, and all of them were found to be genuine jade. Hemudu site of Majiabang culture, the jades produced are fake jade; At the Songze site in Qingpu, Shanghai, the jades produced are mainly genuine jade mixed with fake jade. In the late Liangzhu culture, almost all jades produced at Fanshan and Yaoshan sites in Yuhang were genuine jade. To identify the texture of jade, we should also study its origin, explore the source of ancient jade, and study the communication between different regions and the influence and communication between various cultures.
In addition to archaeological excavations, the identification of jade age also uses the methods of geological stratigraphy and archaeological typology to determine the chronological order of unearthed jade by referring to the age of dating objects and understand its evolution process. Those who have lost their unearthed sites, can't identify the funerary objects and the original environment, and the ancient jade handed down from generation to generation need to be identified and dated.
There are some jades unearthed in China in the early years, which have been handed down for several generations. In recent years, according to the newly discovered archaeological data, scholars have chosen the standard instrument with clear unearthed place and time as the scale to find out the similarities between some ancient jade handed down from ancient times and the above standard instrument in shape and pattern, thus summing up the regionality of some ancient jade and rediscovering the correct time and space. This dating method has been adopted by researchers. Museums and cultural relics collection units at all levels should date, identify fakes, file and classify jade collections. Archaeologists and cultural relics departments identify the authenticity of ancient jade and determine its age by the following ways:
(1) Master the fashion and work style of the times. Choosing archaeological excavation as a standard instrument is helpful to solve the problem of dating from generation to generation. In the absence of unearthed objects to compare, it takes a long time to accumulate visual experience and master the style, development and evolution of jade articles in various eras. Distinguish between the upper limit and the lower limit of an object, and the appraiser will know fairly well when identifying the age. For example, the animal-shaped jade carvings in Shang Dynasty were able to use modelling technique such as realism and exaggeration, and were restricted by the specific ideology at that time, resulting in many excellent works. The jades unearthed from Shang tombs are generally flat reliefs, but when they developed to Mu Hao's tomb, they were round sculptures with more complicated shapes. In the Western Zhou Dynasty, animal-shaped jade was carved with the outline of an animal, just like a silhouette. During the Spring and Autumn Period and the Warring States Period, the jades worn by flat animals were greatly reduced and replaced by jade. Yu Pei is not only related to each other, but also has a certain combination, and pays attention to the symmetry of image and color. In the Warring States period, the ornamentation of Yu Pei became more and more complicated, and the lines were mostly curled and connected, which was very different from the ornamentation in the early Shang and Zhou Dynasties. In the Han Dynasty, the use of jade materials was strictly controlled, and the texture was moist and flawless. In addition, feudal rulers paid less attention to traditional ritual vessels, and their social status was measured by the valuable daily necessities they had before their death and the number of jade articles buried after their death. Valley patterns and Pu patterns, which prevailed in the Warring States and Han Dynasties, all disappeared after the Han Dynasty, and only reappeared when the antique style rose in the late Northern Song Dynasty. The above examples show that with the change of fashion, jade production has left the brand of the times.
2 focus on technology. Because sculptors are related to tools and craftsmen's study habits, it is easiest to inadvertently reveal the style of the times. For example, the Neolithic jade and jade cong were drilled on both sides, and the butt joint was slightly offset, forming a platform mark. During this period, the holes in jade were larger in outer diameter and smaller in diameter as they went inward. At the same time, the surface of the device will leave arc marks hanging on both sides when machining the rope saw; In Shang dynasty, it was a straight line mark left by metal straight saw processing. Hongshan Culture jade noodles like to use the processing method of thinning the edges and hollowing out the center. In Shang Dynasty, the hidden lines with double hooks were used to decorate the details, and the lines followed the radian of modeling. Unique method of jade carving into slope in western Zhou dynasty. During the Warring States period, jade carving tools were greatly improved, and the surface of jade was polished with glass luster and looked sharp. There are hairlike concave carving patterns in the Han jade decoration, commonly known as hairspring carving, and some parts of jade beasts and jade birds are decorated with fine concave carving patterns, which is a production technique with great characteristics of the times. A deep three-dimensional carving technique, which is common in jade carving in Song, Liao and Jin Dynasties. Jade articles made by this technology include Yu Pei and Luding. In the Ming Dynasty, deep three-dimensional carving was changed to double-layer carving with different patterns, such as jade belt decoration. There were vertical sculptures in the Ming Dynasty, but little attention was paid to the side, inner chamber and foot. In the Qing dynasty, the rules were flat and the workmanship was exquisite and meticulous.
③ Compared with other contemporary handicrafts. The style of the times runs through all the process departments in the same period, and there are many places that can be used for reference, exchange, absorption and integration. There are many symbolic and decorative patterns in Shang jade articles, which are basically consistent with bronze crafts. Bird patterns on jade articles in the Western Zhou Dynasty often have a high crown, a large beak and a long tail, which are exactly the same as those on bronzes. In the Spring and Autumn Period, jade ornaments with animal face patterns unearthed from the tombs of Mr. and Mrs. Huang were similar to the patterns on stolen patterned pots. The jade plate ornaments unearthed from the No.1 tomb of Sixia in Xichuan in the Spring and Autumn Period are covered with flat patterns, which are almost consistent with the patterns on the recommended vessels. There are also similarities between the hairspring carving in Han dynasty and the line-carved stone relief in the same period. Jade articles in the Tang Dynasty are called both form and spirit, and the sense of sculpture is enhanced, which is to some extent caused by the influence of paintings and sculptures in the Tang Dynasty. The modeling and decoration of jade articles in this period are also closely related to the gold and silver wares of the same period. Jade articles in Song Dynasty have a strong flavor of life, and their shapes tend to be patterned, which is not unrelated to the painting style of the academy at that time. Apart from the influence of literati painting, jade articles in Yuan, Ming and Qing Dynasties were carved in layers in Ming Dynasty, similar to brocade and Qi Diao.
(4) Looking for supplementary evidence from the literature. For example, from the burial of the jade clothes in Han Dynasty, from its origin, the decorative jade curtain in the Spring and Autumn Period and the Warring States Period, to the decorative jade clothes of gold, silver and copper in Han Dynasty, until the disappearance of the jade clothes, Wei Wendi banned the burial of jade boxes with pearls, and found the literature basis, thus reaching a convincing conclusion on the dating of jade clothes. Jade swords and jade articles in Han dynasty are also found in literature, and jade belt boards became popular in Tang dynasty. Historically, Tang Gaozu gave Li Jing thirteen jade belts, which were a new tribute from Khotan, thus dating the above jade ornaments. The research and dating of "Spring Jade" and "Autumn Jade" in Liao and Jin Dynasties have been confirmed by literature. "Spring jade" refers to the jade with the pattern of stork (Haidongqing) catching goose (swan). "Autumn Mountain Jade" refers to the jade with the theme of tiger and deer in the mountain forest. The former is consistent with the hunting activities recorded by Liao Emperor in Liao History, while the latter is consistent with the activities of Qiu Bona recorded in Liao History. According to the old system of Qidan, the Jin Dynasty called the jade articles with the above themes "self-spring water clothes, mostly with wild goose catching flowers" and "autumn mountain ornaments".
⑤ Micro-detail characteristics and changes. The experts of the older generation have many advantages in this respect. They know all about the changes in the details of various jade articles, such as dragon patterns, shapes and patterns of dragon patterns, and make in-depth and detailed research on jade jade, jade sword ornaments and jade figures. They can point out the track of the changes of the times one by one, and combined with other aspects, their judgments are often very accurate.
⑥ Pay attention to the identification of antiques and fakes. This depends on mastering the characteristics of authentic products in different times, carefully analyzing and comparing them, and finding out the doubts. Fakes are bound to show flaws in some aspects, especially the imitation of ancient jade by future generations, which can be identified.