About the origin of "burning jade"
The origin of "burning jade" is like this, according to legend, in the beginning, when large pieces of jadeite rough were dug up in the Mines of Myanmar, because there were no modern calcite tools, it was not convenient to transport. The locals burn the rough stone, burn it to a certain extent, pour it on the stone with cool water, let the stone expand and crack because of the heat and cold, and then see if there is green inside! But I don't know who later found out that jadeite can also make the color red and become gorgeous because of burning!
In the National Jewelry and Jade Standard, all methods used to improve the appearance (color, clarity or special phenomenon), durability or usability of jewelry and jade except cutting and polishing are called optimization treatment, which includes two categories: optimization and treatment.
Optimization (processing on the basis of the original): heat treatment, bleaching, wax immersion, immersion in colorless oil, dyeing treatment (chalcedony except jasper, agate) and so on.
Treatment (originally not, followed by the treatment method added): soaked with colored oil, filling treatment, soaked wax (turquoise), dyeing treatment, irradiation treatment, laser drilling, lamination treatment, surface diffusion treatment and so on.
Above: Burnt red emerald wool
The burnt red jadeite is not exactly the above two, it is another mutant form.
It is: it was not originally there, but it was forcibly allowed to have it without adding any material.
Optimization: an ugly woman, makeup is beautiful!
Treatment: an ugly woman, forced to go for plastic surgery, filled with silicone, pad the nose, it becomes beautiful!
Burning red: an ugly woman, she has a fever, the burn is very serious, the face has turned red, you think it is a new breed, it feels beautiful.
So the burnt red emerald has not changed anything, or the ugly woman, so after the test she did not wear makeup, did not have plastic surgery, or a goods.
There's a difference here: the difference between heat-treated gemstones and burnt red. During the heat treatment of a gemstone, the color-causing elements inside the gem only change in valence, without changes in composition or structure. Jadeite, by secondary immersion in the jadeite mineral gap and fissure in the gelatinous limonite in the heating process, will lose part of the adsorption water, from the original colloidal substance gradually crystallized into a fine iron or feooh (feooh) microcrystalline aggregate, the change in the physical phase will make the emerald from the original brownish yellow to brownish red ~ bright red, the color becomes bright, but the loss of moisture and the transformation of the physical phase, It will also make the gap between the jadeite jadeite mineral particles that were originally covered by colloidal limonite be fully exposed, and the jadeite will be accompanied by many small dry cracks, the texture will become thicker, the transparency will decrease, and the original delicate roundness characteristics will be lost.
Above: Burnt red jadeite (left) is brightly colored, the boundary line is not obvious, and the natural jadeite (right) color is dark, and the boundary line is clear. Therefore, in fact, burning red should not be counted as natural jadeite, and a [heat treatment] should be added to the certificate.
How to distinguish natural emerald jadeite from "burnt red" jadeite?
Look at the degree of color vividness: natural emerald jadeite is often darker, brownish yellow or brownish red, the color is changeable, there is a sense of layering; the emerald color of "burnt red" jadeite is often a bright red tone, the color is bright, relatively single, no sense of layering;
First, the identification characteristics of burnt red jadeite
Burnt red jadeite (also known as baked jadeite) is an optimized treatment method for jadeite, which usually puts darker, less valuable yellow or brownish yellow jadeite into a furnace and burns it at a certain temperature to make it a bright red.
Above: Burnt red jadeite wool, the color is too bright The boundaries of the burnt red jadeite emerald are blurred and gradually transitioned
First, "burning red" is a physical method of coloring, it does not change its internal structure, has not undergone chemical treatment, so it is still a cargo jadeite. Burnt red jadeite has a much lower market value than natural red jade because its color is not naturally formed. So how to judge whether jadeite jewelry is "burnt red" jadeite?
1. Vividness
Natural red emeralds are often grayish in tone, brownish red, with a variety of colors and a sense of layering; burnt red jadeite is often a bright red, bright color, relatively single, no sense of layering.
2, the texture is delicate
The texture of natural red jadeite is relatively rounded and delicate; the texture of "burnt red" jadeite appears rough, dry and grainy.
3. Color boundaries
The mutant relationship between natural emerald red and other primary colors (white, green or purple), especially where red jade, there will be a distinct boundary; the "burnt red" jadeite color line is not clear, which is a gradient transition relationship.
4. Transparency
The natural jadeite red part will be relatively transparent, especially the transparency of the boundary part will be better; the transparency between the different colors of the burnt red jadeite does not change much, and the red part is sometimes poorly transparent.
5. The degree of surface smoothness
After the polishing of natural emerald, the surface is smooth and flat, and the reflection is bright; "burnt red" jadeite will have fine dry cracks, which will be smooth and weak.
(dyed red emerald)
Second, the identification characteristics of dyed jadeite
Dyed jadeite is commonly known as c goods, which belongs to the processing of jadeite. However, the causes of dyeing red jadeite and natural red jadeite are secondary colors superimposed after the formation of jadeite, and the color agents are also similar, both are iron oxides, so the identification of red jadeite is far more difficult than the identification of green and purple jadeite. The main identification characteristics of red-colored jadeite samples are:
1. Color characteristics
The color of natural red emerald often has a certain gray tone and is not bright enough. Red often exhibits a mutated relationship with the underlying tension, with red being a darker band. The color of red emerald is more vivid, without gray tones, and the color distribution is more uniform. The red color and the base sheet have a gradient relationship, and the red gradually becomes lighter as the appearance goes inward.
2. Structural characteristics
Due to the large number of small fissures and the abundance of secondary minerals in the fissures, the natural red jade forms a typical dendritic and vein-like structure. The material selected for red jadeite often has no cracks or heals the cracks, and the red dye of red jadeite penetrates into the jadeite through the capillary void and fills the gap of the grain, forming a three-dimensional grid similar to the loofah, called the loofah structure.
3. Infrared spectral characteristics
Natural red jade has a typical absorption peak of 3695cm-1. Red-dyed jadeite needs to be constant temperature at a higher temperature for a period of time, which will cause some adsorption water and water-bearing secondary minerals in jadeite to dehydrate, and lack of 3695cm-1 absorption peak.
4. Raman spectral characteristics
Natural jadeite is mainly composed of pyroxene minerals, does not contain the bonding of organic matter, and has no characteristic peaks in the bonding area of organic matter, only raman peaks unique to red jade. The dyed red jade has many Raman characteristic peaks in the 1100cm^(-1) ~ 1700cm^(-1) organic bond junction area, according to which these organic bonding are artificially added stains.