Lapis lazuli is a rare gems, and the blue lapis lazuli artifacts are often very precious. Lapis lazuli is a blue variant of sodalite. The lapis lazuli color is the body color of the Tibetan Buddhist medicinal Buddha.
Zhang Hongyi, a famous geologist in modern China, wrote in the book "Shiya" that "the color of the lapis lazuli is like the sky, or the golden swarf is scattered, and the brilliance is brilliant. If the stars are beautiful, then the ancient stone is "Tianshi" is used for the treasure of heaven. The "Qing Dian Dian Tu" said: "The emperor is facing the belt, and it is decorated with lapis lazuli for the Temple of Heaven."
Lapis lazuli has unique blue, dark blue, light blue and light cyan, etc., according to its color and can be divided into: dark gold and dark blue and thick but not black; Jingelang jujube dark blue and pyrite content More than lapis lazuli minerals; those who gave birth to the light blue and white calcite, named after the ancients used this stone as a stimulating drug. In ancient China, the burial lapis lazuli was: "With its color, this is used in the road to ascend to heaven," and it was used to make the burial of the emperor. Lapis lazuli is a traditional jade imported from China since ancient times, and most of it comes from Afghanistan. The lapis lazuli was developed and used by Central Asian countries as early as 6,000 years ago. China began in the Western Han Dynasty, when the names were "Lanchi", "Golden Dragonfly", "Points" and so on.
Since the Ming and Qing Dynasties, the lapis lazuli "the color is like the sky", the sky is on, so the emperor of the Ming and Qing Dynasties re-emerged the golden stone. Now preserved in the Palace Museum's more than 20,000 pieces of Qing Palace Tibetan jade, less than 100 pieces of lapis lazuli carvings. Good lapis lazuli color is dark blue and pure, no cracks, fine texture, no calcite impurities. It does not contain Venus (pyrite) or has a very beautiful Venus. The lapis lazuli has a hardness of 5 to 6, which is glassy and slightly oily. The world's famous lapis lazuli origins are Afghanistan, Chile, the former Soviet Union and Canada. But the first push for Afghanistan. The lapis lazuli produced in the country has a uniform dark blue to sky blue, and the fine crystal cryptocrystalline structure contains a trace of pyrite, which makes it shine under the sunlight. The lapis lazuli is called a “treasure†by the Arab Muslim countries. The lapis lazuli can be used as jade carving or jewellery. China's lapis lazuli carving process is first-class, especially after the founding of the country, the lapis lazuli ornaments, mountain seeds, pendants, jewelry and so on produced by Beijing Jade Factory are exported overseas. At present, the constant fighting in Afghanistan has made it difficult to import raw materials.
The quality evaluation of lapis lazuli can be based on color, texture, crack, cut and workmanship, and volume (blockiness).
1, color
The color of lapis lazuli is determined by the content of lapis lazuli minerals. If the lapis lazuli mineral content is high, the color is good, otherwise the color is worse. Because the lapis lazuli mineral is blue, lapis lazuli is generally It is also blue, and it is best to use blue, rich, pure and uniform. If white or white spots are interlaced in the color, the concentration, purity, and uniformity of the color are lowered, so the quality is lowered.
2, texture
Texture is also an important factor in evaluating the quality of lapis lazuli. The texture is dense, tough, delicate, with many lapis lazuli minerals, and contains less impurities and other minerals (such as calcite, pyroxene, mica, blue stellite, etc., but may contain a small amount of pyrite with evenly distributed star points), such a green Gold stone is the top grade. If the pyrite is partially distributed in a sheet, it will affect the texture of the lapis lazuli, which in turn will affect the quality of the lapis lazuli. For lapis lazuli, minerals containing impurities uniformity distribution mineral impurities, will also be evaluated for a standard texture, is generally believed that a uniform distribution of mineral impurities who were higher than the uneven distribution of the quality level, the lower the quality level and vice versa.
3, crack
Cracks will significantly affect the quality of lapis lazuli, no crack is best, followed by tiny cracks, the more obvious cracks, the lower the quality grade.
4, cutting and work
Since pure blue lapis lazuli with beautiful, high-quality and therefore, no crack is often used as a jewelery stone lapis lazuli jewelery is often used as cut into a cut-type and flat-type arc-shaped cut. The lapis lazuli cut into flat type is generally the highest quality lapis lazuli jade, and the lapis lazuli jade cut into a curved surface is of lower quality than the lapis lazuli, so according to the shape of the lapis lazuli cut, We can roughly distinguish the quality of lapis lazuli.
When the flat lapis lazuli is evaluated for its cutting, attention should be paid to the outline of the finished product and the thickness of the finished product. The general thickness is not to be less than 2.5 mm. Below this thickness, the quality level will be lowered. For the use of lapis lazuli into jade, it should be noted whether the line of the jade is smooth, whether the curve is round or not, and whether the proportion of the whole piece of jade is appropriate, whether it can produce an overall harmonious beauty.
5, volume (blockiness):
Refers to the size of the lapis lazuli block. Under the same quality factors, the larger the lapis lazuli block (whether it is a jewelry stone or a rough stone), the higher its value.
According to the differences in mineral composition, color and texture of lapis lazuli, lapis lazuli can be divided into the following four quality grades, and the quality is reduced in turn.
(1) Lapis lazuli: the highest quality lapis lazuli. The lapis lazuli mineral content is above 99%, does not contain pyrite, and has few other impurity minerals. The texture is dense, tough and delicate, and it is rich, pure and uniform blue.
(2) Qingjin grade: lapis lazuli mineral content is generally 90-95%, no white spots, can contain sparse star-shaped pyrite and a small amount of other impurity minerals, the texture is pure and dense, delicate, color concentration, uniformity The purity is worse than the lapis lazuli.
(3) Jinkelang grade (Jingelang grade): Among them, the content of lapis lazuli minerals is obviously reduced, containing more and dense pyrite, the content of impurity minerals is obviously increased, there are white spots and white flowers, and the concentration of color is obviously reduced. It is light blue and unevenly distributed.
(4) grading stone grade: This type of lapis lazuli is the worst quality lapis lazuli jade stone, containing the least lapis lazuli minerals, generally does not contain pyrite, while the content of impurity minerals such as calcite is significantly increased, only star-shaped blue on jade Color distribution, or mixed with blue and white motley.
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