Jadeite jade

Chemical composition: sodium aluminum silicate.

Colour: wide range of colours including white, green, yellow, red, orange, violet and black.

R.I.: 1.64-1.67. Usually the refractometer shows only one line near 1.66.

Hardness: 6.5-7. Very tough.

Crystal structure: monoclonic, usually massive.

Specific gravity: 3.25-3.36.

Sources: major sources include Myanmar, Guatemala and Siberia.