Jade stone is a mineral used since prehistoric times, due to its hardness, it was appreciated for making weapons and instruments.
In China, its use was part of the manufacture of figures and religious symbols used in cults of the gods.
Sculpture carved in jade stone
In pre-Columbian Central America, jade was valued more than gold.
In jewelry, around the XNUMXth century, it was discovered that jade was perfect for composing adornments and accessories.
The term jade originates from the Spanish “piedra de ijada”, which means “stone for side pain”.
It received this name when the Spanish, explorers of Central America, saw that the natives used the stone to cure the kidneys.
The Chinese refer to jade as “yu”, which means “heavenly” or “imperial”, and consider it the “stone of the gods”.
In China, jade is considered so precious that there is a Chinese saying: “gold is valuable; jade is priceless.” They believe it has health and longevity enhancing properties.
The Chinese often carve jade into traditional figures that carry even more meaning, such as dragons, which are symbols of power and prosperity.
In New Zealand, jade also plays an important role. It was used for many years in the making of weapons, chisels and hooks.
In 1863, it was discovered in France that the stone known as jade is composed of two kinds of minerals, which were named jadeite and nephrite.
Bracelet made with jade stone
As the distinction between the two is difficult, the term jade continues to be used for both forms:
Jadeite is resistant and hard, composed of sodium and aluminum silicate, in the form of fibers.
Nephrite is a silicate of calcium, magnesium and iron, more resistant than jadeite, formed in reticulated fibrous crystals.
Being rarer, jadeite is more valuable.
Imperial jade is a stunning green jadeite, considered the most valuable.
Both jade and nephrite have beautiful texture, tenacity and colors, ranging from pastel tones to intense, earthy tones and the more familiar green.
In jewelry it is widely used and appreciated.
In the past, some people were so enchanted by it that they became obsessed with it. Over the centuries, in historical accounts, jade appears with an important role, as this obsession ignited wars, such as that of the Chinese Emperor Qianlong, who was fanatical about the gem and invaded ancient Burma in search of its deposits.
The collection of sculptures, pieces and jewelry from the Qin dynasty, which the emperor is part of, is known as one of the largest and most valuable.
Hutton Mdivani jade necklace
The value of jade also encouraged the looting of imperial treasures by the French, British and Japanese, as well as by adventurers and bandits. It even captivated the rich and famous who began to collect pieces with the gem - all of which helped to take its price to the heights.
And all these stories generated the idea of a book, conceived by two journalists – Adrian Levy and Cathy Scott-Clark, who carried out an ambitious study to show the intriguing history of this valuable gem.
In 1997, “Christie” sold the famous jade necklace “Doubly Fortunate” for almost 10 million dollars and, in 2014, this record was broken with the sale of the Hutton Mdivani necklace, with ruby clasp by Cartier for more than 27 million dollars.
Jade Stone - Characteristics, Varieties and History
Jade
gemological characteristics
1. Jadeite
Crystalline system: monoclinic, intergrowth aggregates of fine granules and burrs.
Chemical formula: NaAlSi 2 O6
Hardness: 6 1/2 to 7 mohs
Density: 3,30 - 3,38
Transparency: translucent, opaque.
Color: green, yellow, white, reddish, lavender, gray and black.
Shine: from greasy to pearly.
Fluorescence: faint green, blue-gray.
Fracture: friable.
Refractive index: 1,652 – 1,688.
Jadeite presents a characteristic absorption spectrum in the visible light region, observed through the edges in the most opaque gems.
It has a matte sheen on fracture surfaces which, when polished, becomes a greasy sheen.
2. Nephritis
Crystal system: monoclinic, tangled aggregates of delicate fibers.
Chemical formula: Ca2 (Mg, Fe)5 (Si 4 O11)2 (OH)2
Hardness: 6 to 6 /12 mohs
Density: 2,90 - 3,03
Transparency: opaque.
Color: green, yellow, white, reddish, gray and brown. With frequent spots.
Shine: from greasy to pearly.
Fluorescence: none.
Fracture: brittle, shattered.
Refractive index: 1,600 – 1,627.
Nephrite is a fibrous aggregated variety of the actinolite-tremolite mineral series, so its structure is stronger than that of jadeite.
Most of them show spots and bands, however, specimens with homogeneous colors can be found.
Varieties of jadeite and nephrite
Pure jadeite is white. Both jadeite and nephrite, due to the presence of impurities such as iron and manganese, can appear in different colors as already mentioned.
Colors tend to be pastel and opaque, with the exception of imperial jade, which has a special luster and is translucent or semi-transparent. Jadeites with uniform colors are more valued.
In the West, emerald green, spinach and green apple are considered particularly valuable.
In the Far East, on the other hand, pure white and yellow with a light pink background are very popular.
1. Imperial Jade
It is a jadeite found in Burma, Myanmar. It has an emerald green color from translucent to transparent.
Imperial Jade
It is the most appreciated and sought after variety, and consequently the most expensive.
This vivid color is due to the presence of chromium. Some specimens may have small black inclusions.
Regarding the size, they are smaller, but perfect.
2. Jade Yunan
This is the Chinese name given to jadeite, after the name of the Chinese province through which jade was imported from Burma.
They are lower quality jadeites when compared to imperial jade.
They are found in northern Burma in secondary deposits such as conglomerates or boulders. They are also presented in layers interspersed with serpentine.
3. Gray Jade
Nephrite is often just called jade.
Colors are less delicate and pure than jadeite. They range from dark green (with the presence of iron oxide) to pastel tones (rich in magnesium).
They may have spots, bands or be homogeneous.
The typical shade of nephrite is sage or spinach green.
yellow jade
Very dark green appears to be black. If the nephrite fibers are aligned parallel, it is possible to achieve a “chatoyance” effect (cat's eye effect, shine), which is not achieved with jadeite due to its granular composition.
4. Colored jades
yellow jade
Albite jade – Two varieties are given this name. One is a mixture of jadeite and albite, it's green with black spots, it comes from Burma. The other is a chloromelanite. Composed of kosmoklor, a material related to jadeite, combined with albite, jadeite and other minerals. The presence of chlorite gives it a deep green color with dark green veins and spots. It is also found in Burma.
nephrite jade
red jade
gray jade
white jade
black jade
Color and Dyeing
Jade is often subjected to treatments. Can be bleached with acid to remove pigments or stains.
This treatment makes the gem more porous and more prone to breakage, so the fractures are usually filled with a polymer, which improves their appearance.
This treatment or even a dyeing process can be verified with a “Chelsea filter” (it is a filter that was developed to distinguish pure emeralds from imitations, but it is often used for other gemstones).
red jade
Although a large amount of jade is treated, it is not difficult to find natural jade.
Classification
The Chinese jade industry uses a ranking system to classify jade according to the amount of improvement it has received.
This jade grading system is described in grades – from A to D:
Grade A - Jadeite is not dyed or filled, but may have been coated, is considered stable.
Grade B – may have been filled and bleached but is not dyed.
Grade C – dyed and filled.
polished jade stone
Grade D – not a natural jade.
Cutting and Application
Jade is extremely versatile and can be both cut and carved, even into intricate shapes.
It is carved in a variety of traditional Chinese figures, such as Buddhas, dogs, dragons, bats and butterflies, but also in rounded, geometric, enim shapes, it has many possibilities that vary according to the design of the piece that will use it.
Other options, carved from pebbles and gravel, are beads, in the form of pearls for rings, brooches and pendants.
Whole bracelets are also made from jade.
Most jades are cut in Taiwan, China and Hong Kong.
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