Green is the main color on the earth, and jade is the green deposit, green essence and green soul in the stratum under the dam. After tens of millions of years of melting in the center of the earth, it has become a kind of green jade, beautiful, rare and precious, making jade the crown of jewelry.
Many people don't know much about the identification of jadeite jade. This paper mainly introduces the basic knowledge about jade identification, which is only for your reference when purchasing jade jewelry.
Emerald: When distinguishing jadeite raw materials from finished products, we should pay attention to the interwoven structure of variegated crystals on its polished surface. On a piece of jade, you can usually see two forms of jade, one is granular variegated crystals with slightly larger particles, and the other is fibrous crystals intertwined around the variegated crystals. Under normal circumstances, in the same piece of jadeite, the phenocrysts are uniform in size, which is the top grade.
Stone flower: In a piece of jade, there are usually small pieces of white fibrous crystals with poor transparency intertwined to form stone flowers. Some of these stone flowers and phenocrysts are transparent, while others are slightly transparent to opaque. Transparent is the top grade, slightly transparent is the second, and opaque is the inferior.
Color: Jadeite varies in color, ranging from white, lotus root starch, oily blue, lush green and bean green to dark green and black. There are shadows on the green emeralds. Perfect transparent green is emerald as the top grade, perfect transparent and mottled crystal transparent as the top grade, followed by translucent.
Gloss: The luster of jadeite is bright and transparent, and it has a soft and strong glass luster. Emerald has high density and strong refractive index; It sinks rapidly in tribromomethane, and nephrite such as serpentine jade, grape stone jade and quartzite jade is suspended or floated in tribromomethane. The refractive index of jadeite is 1.63, and the hardness is between 6.7 and 7.4.
Inclusions: Black minerals in jadeite. Inclusions are mostly fused, the edges of particles are loose and turbid, and the green around black inclusions is deepened. It is said that "green with black". The combination of minerals in jadeite and jadeite brings into play the phenomenon caused by chemical changes. People who wear jewelry with green black spots will change the color of ink with time and people after wearing it for a long time and directly touching people's skin.
Strong water holding capacity: refers to dropping a drop of water on the surface of the jade product, and the drop protrudes higher, similar to holding a drop of water in the lotus leaf and dew on the grass tip. In a word, the main distinguishing features of jadeite are: uneven color and persistent green potential; The glass with grease has strong luster; Heterochromatic crystal interwoven structure; Cool, Charles. The color stays the same in the mirror.
How to distinguish jadeite grades
Answer: Jade A goods refer to pure natural jade pieces that are not filled and colored, and are called A goods.
B: If it is filled (for example, filled with high polymer, etc.). ) into b goods; B goods are still mineral components and natural jadeite, and the color is natural, but the aging of the filled colloid will affect the brightness and brightness of its color and the transparency and luster of jadeite.
C: If the colored goods are called C goods; The mineral composition of C goods is the composition of natural jadeite. B+C goods that are filled and colored at the same time.
Emerald constituent minerals
Jade is mainly composed of jadeite in a single pyroxene cluster, or other pyroxene minerals (such as chromic jadeite and omphacite). ) and high jadeite molecule (NaAISi206). The mineral composition of jadeite is considered to be the product of high-pressure and low-temperature metamorphism, which has been confirmed by jadeite synthesis experiments. For example, Aina in jadeite is mostly replaced by calcium, magnesium, iron and Ct. , beyond the scope of English composition, into other pyroxene. Jadeite composed of diopside and aegirine (English, omphacite, diopside, aegirine, etc. ) It is also called "pyroxene jade" but it does not belong to jadeite.
For the identification of jadeite jade, the national standard GB/T 16553- 1966 "Jewelry and Jade Identification" has made more accurate provisions. However, the commercial scope of jadeite is larger than that of jadeite. However, because jadeite is a polycrystalline aggregate, the more accurate method to determine whether jadeite and jadeite are mineral components is electron probe image component analysis. However, due to the limitation of instruments and equipment, the differential oil immersion method is faster and more convenient. As long as an ordinary polarizing microscope and a few bottles of refractive index are immersed in oil, the sample obtained is very small, and even the torus of the top grade will not affect its beauty and value.
The color of jadeite
Emerald green is the treasure of jade, and green is regarded as the top grade. There is a jargon that "the higher the color, the higher the price is ten times". Therefore, the coloring technology of jadeite is constantly innovating. Besides home red and purple, there are at least four kinds of green varieties on the market. Green jade that looks like natural emeralds, its value is only 1% to11000 of goods A, even lower than that of goods B. Colorless jade is dyed into brilliant green jade and sold as high-grade jade, which makes some consumers suffer huge losses and mental burdens.
The jadeite colored with chromium salt in the early days was red by Charles filter (natural green garnet was also red), and a number of jadeite rings were dyed with chromium salt, which was discovered by American Gemmology Institute as early as 1956. At present, many dyed jadeites do not use chromium salts, and the characteristics under the inspection mirror are similar to those of natural jadeites, so the inspection color filter can only be used as a reference. In the jadeite dyed before, it can be seen that the color grade is precipitated in the reticular Levine. Now some green jadeite colors (including some B+C ornaments or pieces) can't see this phenomenon, so there is no trace of pigment precipitation in the cracks. In that case, it may not be A goods. In recent years, a kind of jade bracelet and pendant with uneven light green dyeing is common in the market and sold as natural jade. This kind of jewelry is soft in color, has certain transparency (refers to water) and does not need glue injection. Under the spectroscope, the absorption line at 437nm is clear, and the tapping sound, ultraviolet fluorescence characteristics and Charles filter observation are basically the same as those of natural jadeite. The retail price of this bracelet is generally 500- 1500, which is popular with ordinary working-class people and tourists. According to the data of many experiments, the micropores are filled with dyes (partially polished chromium powder). Due to the reflection of light, the jadeite in the dyed part is light green. Some dyes are dyed as a whole, some are burned directly, and some are accompanied by purple (also known as "spring color", which is a multi-dyeing method). It is a special kind of bracelet, with several light green and several lavender segments.
If you soak in solvents such as detergent (if necessary, use ultrasonic cleaning), you can wash off most of the dyes, but generally it will leave a faint green after cleaning. With a magnifying glass of 10 times (obviously it can be seen with the naked eye), you can see the silk slightly dyed dark green in the cave. Dyed and washed products are lighter in color, but more natural and deceptive, which is difficult for ordinary consumers to identify. It is also common for some bosses with certain business experience to see that they become bulk purchases, fall for it themselves, and then pass it on to consumers. Even if professional jewelry inspectors are slightly negligent, it is possible to regard this dyed jade as natural jade and issue a qualified inspection report.
There are many subjects for jadeite identification. Here, we dedicate the elements to the common sense of jade.