Just as the country needs to promulgate laws and regulations to be the code of conduct for people, jadeite also needs a standard in order to give everyone a more comprehensive and professional understanding of jade. The National Standard for Jadeite Classification, organized by the Jewelry and Jade Jewelry Management Center of the Ministry of Land and Resources, was implemented on March 1, 2010. It is China's first national standard for jade grading.
Xiao Bian deliberately selected 10 points of professional grading knowledge about jade, hope that Cuiyou can understand and understand the jade national standard more clearly, thus forming a professional jade system, to be a professional jade player.
Definition of jade
On the basis of a large number of tests and analysis, based on the principle of scientificity and operability, the national standard defines jade as: “Jadeite is mainly composed of jadeite or jadeite and other sodium and soda-lime pyroxene (sodium chromite. , omphacite, a mineral aggregate with process value, the mineral composition of jadeite may contain a small amount of minerals such as amphibole, feldspar, chromite ore.
The main parameters:
a. Hardness hardness 6.5-7;
b. density 3.34 (±0.06-0.09) g / cm3;
C. refractive index 1.666 ~ 1.680 (± 0.008);
d. Point side 1.65 ~ 1.67.
2. Classification of jade
The jade is rich in color. According to the color of jade, the jade is divided into jade (colorless), jade (green), jade (purple) and jade (red-yellow).
Category Description:
a. Emerald (colorless) refers to jade with no color or very low chroma;
b. Emerald (green) refers to the jadeite with a color tone of green color and a certain chroma;
c. Emerald (purple) refers to jadeite with a color tone of purple color and a certain chroma;
d. Emerald (red-yellow) refers to the emerald color with a reddish-yellow color and a certain chroma.
3. Color grading
When the transparency, texture and clarity are the same, the value of color jade is much higher than the value without color jade. Therefore, the color weight is the largest among the elements of the jade rating, and the color classification is jade grade. Focus. In the National Standard of Jade Grading, the color classification of jadeite is carried out according to the three elements of color.
Three elements of color:
a. tone classification;
b. chroma grading
c. Lightness rating.
4. Tone classification
In the spectrum of visible light, the green left and right grading is blue and yellow, so jade (green) is often accompanied by blue and yellow in addition to green, because jade (green) color is divided into: green, green (light blue ), green (light yellow) three types.
5. Chroma rating
Chroma is what people usually say about color saturation, also known as concentration. The jade chroma is divided into five levels according to the degree of color shading: extremely thick Ch1, thick Ch2, thicker Ch3, lighter Ch4, and light Ch5.
6. Brightness classification
Brightness refers to the degree of light and darkness of the jade color, which is commonly known as "yang" in the "Positive Zhengyanghe". According to the brightness of the jade, it is divided into four levels: bright V1, brighter V2, darker V3, and darker V4.
7. Transparency classification
The transparency of jadeite refers to the degree of transmission of jade to visible light. Emerald (colorless) transparency is divided into 5 levels. Transparent T1, sub-transparent T2, translucent T3, micro-transparent T4, opaque T5. Emerald (green) transparency is affected by color, chroma is increased, brightness is reduced, transparency is also reduced, and the effect of color on transparency is excluded. The transparency of jade (green) is divided into 4 levels. Transparent T1, sub-transparent T2, translucent T3, micro-transparent ~ opaque.
8. Texture classification
The fineness and roughness of the jade texture are determined by the size of the crystal grains. The crystal grains are small, the texture is fine, and the crystal grains are large, and the texture is rough. The texture level is divided into five grades according to the particles of the jadeite mineral: very fine Te1, fine Te2, finer Te3, coarser Te4, and coarse Te5.
9. Clarity rating
According to the influence of inclusions on the beauty and durability of jade, the clarity is divided into five levels: extremely pure C1, pure C2, pure C3, pure C4, and impure C5.
10. Jade craft evaluation
The value of jade jewelry depends not only on the quality of jade but also on the processing technology of jade. The good processing technology can greatly enhance the value of jade jewelry. Therefore, the evaluation of jade jewelry should also include the evaluation of processing technology.
The Jade Process Ratings stipulates that the jade process evaluation includes two aspects: material application design evaluation and processing process evaluation. Material application design evaluation includes material application evaluation and design evaluation; processing technology evaluation includes grinding (engraving) process evaluation and polishing process evaluation.
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