Green Jade

Green jade refers to the green forms of two distinct but similar tough gem materials: jadeite (a pyroxene) and nephrite (an amphibole). Both have been carved for thousands of years and are collectively called jade.

Jadeite is rarer and can reach the most vivid "imperial" emerald green, the most valuable jade color, colored by chromium. Nephrite ranges from creamy to deep spinach green and is colored by iron.

Jade's defining quality is its extraordinary toughness, an interlocking fibrous or granular microstructure that resists breaking even though it is only moderately hard. This made it ideal for tools and intricate carvings in ancient China, Mesoamerica and among the Maori of New Zealand.

Both jades form in metamorphic settings. Jadeite crystallizes under high pressure and relatively low temperature in subduction-zone environments, typically associated with serpentinite, with the premier source being Myanmar (Burma); Guatemala and Russia also produce jadeite.

Nephrite forms where serpentinized ultramafic rocks or dolomitic marbles are altered, producing its tough mat of tremolite-actinolite fibers. Important nephrite sources include China, Russia (Siberia), Canada (British Columbia), New Zealand and Wyoming.

Because jade is so tough and resistant, it often survives as boulders in rivers and alluvial gravels, traditionally collected from streambeds.

Look for a tough, dense green stone with a greasy to waxy luster when polished, hardness 6-7, and translucency ranging from opaque to semi-transparent. Jade has remarkable toughness, it resists chipping and rings with a clear tone when tapped.

Jadeite tends to show a slightly dimpled "orange peel" surface and can be vividly green; nephrite is more fibrous, often spinach to creamy green. Streak is white.

Look-alikes are common, including serpentine, aventurine quartz, green glass, dyed quartzite ("Malaysia jade") and chrysoprase. These are generally softer or less tough; serpentine is softer (2.5-5.5), and glass shows bubbles. Professional testing is often needed to separate jadeite from nephrite and from imitations.

Green jade is prized for carvings, bangles, beads, cabochons, pendants and ornamental objects, with fine imperial jadeite among the most valuable gem materials in the world, especially in East Asian markets.

Historically it was worked into axes, weapons and ritual objects because of its toughness, and it holds deep cultural significance in China, Mesoamerica and Maori culture (pounamu).

Metaphysically, jade is associated with luck, prosperity, harmony and protection, though these claims are not scientific. Buyers should beware of dyeing and polymer impregnation, which are common treatments.