For centuries jade was thought to be a single gemstone, but in 1863 two types were recognized: jadeite and nephrite. Nephrite is more common, but both are tough, fine-grained rocks, suitable for carving. Jadeite, made up of interlocking, granular pyroxene crystals, occurs in a wide range of colors including green, lilac, white, pink, brown, red, blue, black, orange and yellow. The most prized variety, imperial jade, is a rich emerald green, due of chromium. Jadeite commonly has a dimpled surface when polished.

Jadeite is found in metamorphic rocks and as alluvial pebbles and boulders. Some boulders develop a brown skin, due to weathering, and this is often incorporated into carvings and worked pieces. The most important source of jade is Burma, which has supplied China with translucent imperial jade for over 200 years. Historically, Guatemala was an important source of jade, providing the material for the carvings of the Central American Indians. Jadeite also occurs in Japan and California (USA).

The Spanish conquistadores adopted the use of jadeite when they invaded Central America, and often wore amulets made from it. They called it piedra de hijada (loin stone) or piedra de los rinones (kidney stone), believing it prevented or cured hip and kidney complaints

Chemical Composition: 

Sodium Aluminium Silicate - NaAl(SiO₃)2

Classification / Type: 

Belongs to the pyroxene group of minerals.

Colors / Varieties: 

All colors from white, green, lilac, pink, brown, yellow, grey to black. Highly valued color is emerald green known as Imperial Jade.

Transparency: 

Semi-transparent to Opaque

Crystal System / Forms: 

Monoclinic System / Cryptocrystalline, consists of interlocking crystals as boulders.

Hardness: 

7

Specific Gravity: 

3.30 - 3.36

Cleavage / Fracture: 

Not visible / Granular fracture.

Optic Character: 

Anisotropic, D.R.; Aggregate (A.G.G.)

Lustre: 

Vitreous to greasy.

Refractive Index / Birefringence: 

1.654 - 1.667 (Spot R.I. 1660) / 0.013

Pleochroism: 

None.

Magnification: 

• A dimpled effect is seen on the surface, due to differences in hardness of the grains.
• Dyed jadeite (green): color concentrations along cracks.

U.V. Fluorescence: 

Varies with colors.

Spectrum: 

• Green jadeite (Cr %): 437.5nm, doublet at 690nm, other lines at 630nm, 655nm may be seen.
• Dyed green jadeite: 437.5nm, band at 650nm.

Cause of Color: 

• Emerald green - Chromium
• Duller green - Iron
• Yellow, brown - Iron
• Lavender - Manganese

Treatment (Enhancement): 

• Bleaching: used to remove color discrepancies and provide a uniform color.
• Coating
• Colorless impregnation: a specific example is B - Jade. This is low quality jadeite which is initially bleached and then polymer treated to produce a more uniformly colored and durable material.
• Colored impregnation (dyeing): dyed green and lavender commonly.
• Heat treatment: jadeite containing yellow brown iron is heated to give reddish brown colors.

Specific Tests: 

Very tough mineral (but not the hardest).

Synthesis: 

Prevalent but not in commercial use.

Simulants (with separation tests): 

Nephrite (R.I., S.G., structure, spectrum), Synthetic Jadeite (slightly higher hardness, no spectrum), Composite (junction plane, inclusions), Serpentine (R.I., S.G., lustre, hardness), Idocrase (R.I., spectrum, structure), Hydrogrossular Garnet (R.I., S.G.), Prehnite (R.I., birefringence, structure), Aventurine Quartz (R.I., S.G., structure, spectrum), Maw-sit-sit (color, structure).

Geological Occurrence: 

As alluvial boulders in metamorphosed rocks as nodules, in serpentine

Sources: 

Myanmar, U.S.A. (California), Russia, China, etc.

Cuts & Uses: 

Cabochons, beads, carvings, etc.