Jadeite jade was formed at comparatively low temperatures of around 200-300 degrees C under a pressure of 10,000 atmospheres. Whilst China is widely regarded as the home of jade carving, jadeite jade deposits have not yet been found within the boundaries of China. The best and largest deposits of jadeite jade still remains in Myanmar.
Jadeite jade occurs in a variety of colours; white, purple, various types of green, black, yellow and red. These are divided into 2 categories, namely primary and secondary colours.
Primary colours, such as white, black, purple and green occur due to partial substitution of the aluminium ions in the jadeite structure. Pure jadeite is colourless or white but if chromium or iron replaces the aluminium, the resulting colour is green.
Secondary colours such as red or white occur after the jadeite jade is exposed to weathering at the surface of the earth. Oxidation decomposes the surface and solutions containing ferrous oxide infiltrate the jadeite jade to form limonite and hematite within the structure of the stone to give rise to yellow or red colouration.
The principles of jadeite jade appraisal rests on 4Cs (Colour, Clarity, Cutting, Cracks); 2Ts (Transparency, Texture) and 1V (Volume).
Value is determined by the purity, intensity, brightness and evenness of colour.
Inclusions are acceptable to a certain degree but rarity in better clarity would affect the value of the piece.
Jadeite jade used to manufacture polished cabochon stones is usually of higher quality and free of cracks and fissures; hence it is most valuable.
Cracks is differentiated from veins. A crack is the discontinuity across the crystal aggregate while the vein is the pattern of well-oriented crystals in the stone.
This is very important for the aesthetic appreciation and value of the jadeite jade.
This refers to the coarseness or fineness of the grains; hence it is closely related to the transparency of the jadeite jade.
In comparing jadeite jade of the same quality, the greater the volume of the stone, the higher the price, especially in the imperial grade of jadeite jade.