Jade or “yu” (meaning precious stone) as it is called in China, is the family name for Jadeite and Nephrite. The term Jade refers to a fine-grained, mineral aggregate composed of either one or both of two other minerals: Jadeite and Nephrite. All jade is composed of highly intergrown, interlocking crystals of one or both of these minerals.
Jadeite is a silicate of sodium and aluminium within the pyroxene group, and has a wide range of colors from emerald green (known as Imperial Jade), to all manner of green shades, purples, pinks, red, brown, orange, blue, black, and yellow! Imperial Jade, the most coveted, is a deep rich green due to the content level of chromium. When polished, Jadeite commonly has a dimpled surface.
Nephrite is a silicate of calcium and magnesium of the amphibole group, and it is often banded or blotchy, and homogeneous in color. It varies from a dark green (due to iron) to a cream color (which would be high in magnesium) with many shades in between, but no other varying colors.
It is said that in Chinese tradition, Jade symbolized all five virtues of humanity: Wisdom, Compassion, Justice, Modesty and Courage, therefore often symbols of these virtues were carved into pieces of Jade.