Gem library
Nephrite jade
The toughest stone, China's green gold
Nephrite jade is the toughest stone in the mineral kingdom: its structure of interlocking fibres resists impact better than tempered steel. That is what made it, for eight thousand years in China, the most precious material of all — long before gold and jadeite.
- Hardness (Mohs)
- 6 – 6.5
- Density
- 2.90 – 3.03
- Crystal system
- Monoclinic
- Refractive index
- 1.600 – 1.627
- Cleavage
- None usable (fibrous structure)
Mineralogical identity
- Family
- Silicates — inosilicates, amphibole group
- Species
- Actinolite-tremolite (series)
- Variety
- Nephrite, mutton-fat jade, river jade
- Chemical formula
- Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂
- Crystal system
- Monoclinic (interlocking fibrous aggregate)
- Classification
- Semi-precious stone
- Rarity
- Uncommon
- Indicative price
- €1 – 500/ct (imperial mutton-fat jade: far beyond)
Etymology
Jade comes from the Spanish piedra de la ijada, «stone of the flank», which conquistadors believed effective against kidney colic — hence also nephrite, from the Greek nephros, kidney.
Physical & optical properties
- Hardness (Mohs)
- 6 – 6.5
- Density
- 2.90 – 3.03
- Refractive index
- 1.600 – 1.627
- Birefringence
- 0.027
- Cleavage
- None usable (fibrous structure)
- Fracture
- Splintery
- Lustre
- Greasy to waxy
- Diaphaneity
- Translucent to opaque
- UV fluorescence
- None
- Pleochroism
- None
- Colours
- green, white, grey-green, brown, black
Formation, geology & history
Two jades, a millennia-old confusion
The word jade covers two distinct minerals. Nephrite, a calcic amphibole of the actinolite-tremolite series, is China's historic jade, from the Neolithic to the eighteenth century. Jadeite, a sodic pyroxene, arrived late from Burma and constitutes «imperial jade», translucent emerald green, today infinitely more expensive. The distinction was only established in 1863 by the French mineralogist Alexis Damour. To the eye, nephrite and jadeite look alike, but their density (2.95 against 3.3) and index differ, and jadeite has a granular look where nephrite is fibrous. Any other green stone — serpentine, aventurine, dyed quartzite — sold as jade is an imposture.
Toughness, the sovereign property
Nephrite's hardness of 6 to 6.5 is modest: a mere grain of quartz scratches it. But its toughness — resistance to breaking — is the highest of all natural stones, thanks to a felt of microscopic fibres interlocked in every direction: a crack cannot propagate in a straight line. That is why Neolithic cultures made axes, chisels and weapons from it rather than jewellery, and why rings and chains can be carved from a single piece, impossible with any other gem. A struck nephrite object rings clear and long, like a bell — hence the Chinese use of jade lithophone chimes.
Eight thousand years of Chinese culture
In China jade is the moral stone: Confucius saw in it the image of the sage's virtues, and the character 玉 (yù) enters dozens of words of value. The Liangzhu and Hongshan cultures, from 5000 BC, produced bi discs and cong tubes of astonishing workmanship given the tools available: jade is not cut but abraded away with sand, which takes weeks for a single perforation. Elsewhere, the Maori of New Zealand developed an equally profound tradition with pounamu, and Mesoamerican cultures worked Guatemalan jadeite.
How to recognise it
- A clear, sustained ringSuspend the piece and tap it gently: nephrite rings like a bell, at length. Serpentine and glass sound dull and short.
- Greasy lustre and fibrous texturePolished, jade has a characteristic oily sheen. In grazing light a fine fibrous felt is visible, never grains or bubbles.
- Coolness and densityDensity 2.95: heavy in the hand, and it stays cool for a long time against the cheek. Serpentine (2.6) is lighter and softer.
Imitations, treatments & confusions
- Serpentine («new jade», «Korean jade»)The most widespread imitation. Far softer (3-5), it is scratched by a knife, sounds dull and feels lighter.
- Dyed quartzite and glassDyed quartzite shows colourant in microfractures; glass has bubbles and an over-vitreous lustre. Neither has jade's ring.
- Treated jadeite (type B and C jade)Jadeite bleached with acid then resin-impregnated (type B) or dyed (type C) is sold as natural jade. It is fragile and its value collapses: a certificate is indispensable above a few hundred euros.
Deposits & origins
China (Xinjiang, Hetian — mutton-fat white jade, the absolute benchmark), Canada (British Columbia, today's leading world producer), Russia (Siberia, spinach-green jade), New Zealand (Maori pounamu), Taiwan, United States (Wyoming), Australia
Care & precautions
- Warm soapy water and a soft brush: nephrite is robust and non-porous.
- Ultrasonic-safe on sound natural pieces — but never on type B jade, whose resin would degrade.
- Insensitive to sunlight. Avoid strong acids and violent thermal shock.
- Many antique jades are waxed: avoid very hot water and solvents that would remove that finish.
Traditions & crystal healing
- Chakras
- Heart
- Zodiac signs
- Libra · Virgo · Pisces
- Element
- Earth
A stone of longevity, harmony and moral virtue in Chinese tradition, far more than a stone of power: it represents the accomplished person — hard but smooth, resonant yet discreet. The Maori see in it a link with the ancestors, and the hei-tiki pendant is passed down as an inheritance.
The virtues described here belong to tradition and cultural heritage. They are in no way medical advice and never replace a consultation.
Frequently asked questions
Nephrite or jadeite?
Two different minerals. Nephrite is a fibrous amphibole, density 2.95, the historic Chinese jade. Jadeite is a granular pyroxene, density 3.3, which yields Burmese «imperial jade», infinitely more expensive.
How do I recognise fake jade?
The sound is the most telling test: jade rings clear and long, serpentine and glass sound dull. Also check the hardness (jade resists a knife) and the greasy lustre.
What is type B jade?
Jadeite bleached with acid then resin-impregnated to improve transparency. The treatment permanently weakens the stone and halves its value: it must be declared and a certificate detects it.