Jade is a mineral that has been used since prehistoric times. Because of its hardness, it was valued for making weapons and instruments.
In China, it was used in the manufacture of religious figures and symbols used in the worship of the gods.
Sculpture carved in jade
In pre-Columbian Central America, jade was more highly valued than gold.
In the 17th century, it was discovered that jade was perfect for jewellery and accessories.
The term jade comes from the Spanish “piedra de ijada”, which means “stone for side pains”.
It got its name when the Spanish, explorers of Central America, saw the natives using the stone to heal their kidneys.
The Chinese refer to jade as “yu”, meaning “heavenly” or “imperial”, and call it the “stone of the gods”.
In China, jade is considered so precious that there is a Chinese saying: “Gold is precious, jade is priceless”. They believe it has health-promoting 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.
Jade also plays an important role in New Zealand. For many years it was used to make weapons, chisels and fish hooks.
In 1863 it was discovered in France that the stone known as jade was actually made up of two types of mineral, jadeite and nephrite.
Jade stone bracelet
As it is difficult to distinguish between the two, the term jade is still used for both forms:
Jadeite is tough and hard, made up of sodium and aluminium silicate in the form of fibres.
Nephrite, on the other hand, is a silicate of calcium, magnesium and iron that is more resistant than jadeite and is formed into cross-linked fibrous crystals.
Being rarer, jadeite is more valuable.
Imperial Jade is a striking green jadeite and is considered the most valuable.
Both jade and nephrite have a beautiful texture, toughness and colours ranging from pastels to intense earthy tones and the most famous green.
They are widely used and valued in jewellery.
In the past, some people were so enamoured of it that they became obsessed with it. Over the centuries, jade has played an important role in historical accounts, as this obsession has led to wars, such as that of the Chinese emperor Qianlong, who was so obsessed with the gemstone that he invaded ancient Burma in search of its deposits.
The emperor’s collection of sculptures, objects and jewellery from the Qin dynasty is considered one of the largest and most valuable in the world.
Hutton Mdivani Jade Necklace
The value of jade encouraged the plundering of imperial treasures by the French, British and Japanese, as well as by adventurers and bandits. It also captivated the rich and famous, who began to collect pieces of the gem – all of which helped to drive up its price.
And all these stories gave rise to the idea of a book, conceived by two journalists – Adrian Levy and Cathy Scott-Clark – who undertook an ambitious study to reveal the fascinating history of this precious gem.
In 1997, Christie’s sold the famous “Doubly Fortunate” jade necklace for nearly $10 million, and in 2014, this record was broken with the sale of Cartier’s Hutton Mdivani necklace with ruby clasp for more than $27 million.
Pedra Jade - Características, Variedades e História
Jade
Gemological Characteristics
1. jadeite
Crystal system: monoclinic, intergrown aggregates of fine granules and bireoles.
Chemical formula: NaAlSi 2 O6
Hardness: 6 1/2 to 7 Mohs
Density: 3.30 – 3.38
Transparency: Translucent, opaque.
Colour: Green, yellow, white, reddish, lavender, grey and black.
Lustre: greasy to pearly.
Fluorescence: pale green, greyish blue.
Fracture: friable.
Refractive index: 1.652 – 1.688.
Jadeite has a characteristic absorption spectrum in the visible light range, which can be seen through the edges of the more opaque gems.
It has a dull lustre on fractured surfaces, which becomes a greasy lustre when polished.
2. Nephrite
Crystal system: monoclinic, tangled aggregates of delicate filaments.
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.
Colour: Green, yellow, white, reddish, grey and brown. Often mottled.
Lustre: greasy to pearly.
Fluorescence: none.
Fracture: fragile, cracked.
Refractive index: 1.600 – 1.627.
Nephrite is an Iberian variety of the actinolite-tremolite series of minerals, which is why its structure is stronger than that of jadeite.
Most of the specimens are mottled and banded, but it is also possible to find specimens with homogeneous colours.
Varieties of jadeite and nephrite
Pure jadeite is white. Both jadeite and nephrite can vary in colour due to the presence of impurities such as iron and manganese, as we’ve already mentioned.
The colours tend to be pastel and opaque, with the exception of Imperial Jade, which has a special lustre and is translucent or semi-translucent. Jadeites with uniform colours are more highly valued.
In the West, emerald green, spinach green and apple green are considered particularly valuable.
In the Far East, pure white and yellow with a light pink background are highly prized.
1. imperial jade
This jadeite is found in Burma, Myanmar. Its emerald green colour ranges from translucent to transparent.
Imperial Jade
This is the most prized and sought after variety, and therefore the most expensive.
The vivid colour is due to the presence of chrome. Some specimens may have small black inclusions.
They are smaller in size but perfect.
2. Yünan Jade
This is the Chinese name for jadeite, derived from the name of the Chinese province through which jade was imported from Burma.
These are lower quality jadeites compared to imperial jade.
They are found in northern Burma in secondary deposits such as conglomerates or pebbles. They are also found in layers interspersed with serpentine.
3. Grey Jade
Nephrite is often simply called jade.
Its colours are less delicate and pure than those of jadeite. They range from dark green (containing iron oxide) to pastel colours (rich in magnesium).
They can be mottled, banded or homogeneous.
The typical colour of nephrite is sage or spinach green.
Yellow Jade
Very dark green appears black. If the nephrite fibres are parallel, a “chatoyance” effect (cat’s eye effect, sparkle) can be achieved, which cannot be achieved with jadeite due to its granular composition.
4. Coloured Jades
Yellow Jade
Albite Jade – There are two varieties called this. One is a mixture of jadeite and albite, green with black flecks, and comes from Burma. The other is a chloromelanite. It is composed of kosmoklor, a material related to jadeite, combined with albite, jadeite and other minerals. The presence of chlorite gives it a deep green colour with dark green veins and flecks. It is also found in Burma.
Nephrite Jade
Red Jade
Grey
Jade
White Jade
Black Jade
Colour and dyeing
Jade is often treated. It can be bleached with acid to remove pigments or stains.
This treatment makes the gem more porous and prone to fracturing, so the fractures are usually filled with a polymer to improve their appearance.
This treatment, or even a colouring, can be checked with a “Chelsea screen” (a screen developed to distinguish genuine emeralds from imitations, but often used for other gems as well).
Red Jade
Although a lot of jade is processed, it is not difficult to find natural jade.
Grading
The Chinese jade industry uses a grading system to classify jade according to the amount of improvement it has undergone.
This jade grading system is described in grades – from A to D:
Grade A – the jadeite is neither coloured nor filled, but may have been coated and is considered stable.
Grade B – may be filled and bleached but is not coloured.
Grade C – dyed and filled.
Cut Jade Stone
Grade D – not natural jade.
Cutting and Usage
Jade is extremely versatile and can be both cut and carved into intricate shapes.
It is carved into a variety of traditional Chinese figures such as Buddhas, dogs, dragons, bats and butterflies, but also into rounded, geometric shapes, in short, it has many possibilities that vary according to the design of the piece that will use it.
Pebbles and gravel are also used to make beads for rings, brooches and pendants.
