What is the reason why jadeite is colorful?
Color mechanism of jadeite
The colors of jadeite are varied, which is also the value of jadeite. The common colors of jadeite are: white, colorless, various shades of green, red, yellow, purple, black, gray and so on.
There are two reasons for the color of jadeite, namely primary color and secondary color.
1, the original color of jadeite.
The primary color of jadeite refers to the color produced by the primary minerals that make up jadeite, which is the main color type of jadeite and the most important factor for jadeite to become a gem. There are many primary colors of jadeite, such as white, green, purple, dark green and black. According to the current research results, the color of jadeite is related to the types of its constituent minerals and their chemical composition. Transparent to translucent jadeite is related to jadeite containing chromium, light green jadeite is related to jadeite containing a small amount of Cr, opaque green jadeite is related to jadeite containing Mn, purple jadeite is related to jadeite containing Mn, some grayish green jadeite is related to omphacite, and the black in jadeite is mostly related to amphibole.
2. The secondary color of jadeite
The secondary color of jadeite refers to the color that jadeite undergoes supergene geological action on the surface or near the surface, which decomposes or semi-decomposes the constituent minerals of jadeite, and fills cracks and micro-cracks of various sizes among mineral particles with oxides, colloidal substances and clay minerals. The main colors are brownish yellow, brownish red, grayish green and grayish black.
The secondary color of jadeite can be divided into oxidation secondary color and reduction secondary color.
1, oxidized secondary color
The main component of oxidized secondary color is Fe3+ oxide, which forms reddish-brown jadeite, also known as Hong Fei. It is caused by the compound containing high valence iron filling in the cracks and particle gaps of jadeite. Because the secondary oxidation is from the outside to the inside, the red dragonfly is distributed in the outer layer of jadeite seed material, and red skin, bovine blood fog and fresh jade are formed from the outer layer inward, and the color of bovine blood fog is often darker than the red skin, which is also the color distribution (color shape) feature of natural red dragonfly. Secondary minerals are distributed in various cracks of jadeite, so maroon-brownish yellow forms a typical root structure.
Under normal circumstances, maroon jadeite has loose structure, poor transparency and not bright enough color, which belongs to middle and low grade jadeite.
2. Restore secondary color
The main component to reduce the secondary color is the compound containing Fe2+, which produces gray-green and brown-green jadeite, which is called oil-green species. It is caused by the compound containing low-valent iron filling in the small cracks and particle gaps of jadeite. These secondary minerals are distributed in various cracks of jadeite, forming a typical root structure. At the same time, the oil cyan is distributed in the secondary inner layer of jadeite seed material, and the zoning of black skin, oil cyan and fresh jade is formed inward from the outer skin, and there is often a very clear boundary between oil cyan and fresh jade. The grayish brown substance filled in the small cracks of jadeite forms a typical root structure.
Oil green is darker and not bright enough, but its transparency is often better. This is also the reason why oil green species become ordinary low-grade jadeite.
Various secondary colors can be superimposed on the primary color, which makes the primary color have various gloomy tones, resulting in the decline of color brightness. Experts call this situation "dirty bottom".
What are the color-causing elements of jadeite?
1, so how did so many colors come from? In fact, the color of jadeite is mainly caused by isomorphic substitution of trace elements such as chromium, titanium, iron and manganese. The higher the content, the darker the color, and the less the content, the lighter the color. Color-causing elements in jadeite are often unevenly distributed, so local colors may be thick or light, or thick or scattered.
2. Green jade, green is mainly caused by Cr (Cr) in minerals, because trivalent Cr is green, and the reason why green is different is because the content of Cr is different. If it is too thick, it will be green or even black, with too little content and too light color.
Purple jade is also called violet, and experts also call it "spring". Purple also has many shades, the common ones are pink purple and eggplant purple. We generally think that purple is caused by Mn (manganese ion).
4. Red jadeite includes brown-red and true-red, which are called Hong Fei and yellow jadeite. Pure red with no earthy hue at all has the highest value. Red is the color formed by the infiltration of limonite (Fe element) into the interior. There are many colors on a piece of jade because it contains many elements. Each piece of jade contains more than one chromogenic element, and they often coexist, but the content is different.
neutral
That is colorless and transparent. This jadeite has a single composition, fine mineral particles, compact structure, consistent optical properties of mineral particles and good transparency, such as colorless old pit glass jadeite.
white
White jadeite has a single composition, but its structure is loose. There are certain gaps between crystal mineral particles, leaving air or other substances, which reduces the transparency and makes jadeite opaque and white.
green
Green is a common color of jadeite, and "Cui" refers to green jadeite. The green color of jadeite can be divided into light green, green, emerald green, dark green and dark green, among which emerald green is the best. Most green jadeites contain variegated colors more or less, showing yellow-green, gray-green, blue-green and other colors. If the yellow tone in yellow-green is very light, it will become yellow-yang-green, but it will not lose the luster of jade, while gray-green and blue-green will affect the color of jade.
purple
Purple jade is also called violet. According to its depth, it can be light purple, pink purple, purple, blue purple or even close to blue.
black
There are two kinds of jadeite black, one is black under ordinary light source and dark green under strong light source, and the other is dark gray to grayish black jadeite, which is caused by hornblende and other dark minerals and looks dirty. It is a relatively low-grade jadeite.
Yellow and red
Yellow and red are secondary colors, which are called "non" in business. When white, purple or green jadeite is formed, hematite or limonite slowly infiltrates along the gaps between jadeite particles due to weathering. Generally, yellow is mostly caused by limonite, and reddish brown is mostly caused by hematite.
secondary color
In the jewelry industry, some color combinations of jadeite have been given some specific names, such as Spring Ribbon, Fu Lushou and so on. Spring ribbon color: purple and green alternate, indicating that spring flowers are in full bloom. Fu Lushou: Green, red and purple appear on a piece of jade at the same time, symbolizing auspiciousness and representing three happiness of life. Emerald is rich in color, and its shape combination and depth distribution are ever-changing. Sometimes there are five colors on the same material, which is also called "multicolored jade".
Evolution history of white jade
Welcome to pay attention to the evolutionary history of jade white. Cui focuses on the knowledge sharing of the jade jewelry industry, and continues to work hard on the road of "white to white, white to big coffee" to discuss the study and research of the jade jewelry industry with you.