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Tuesday, November 07, 2006

How to judge Jade

What is jade?
Jade is one of the oldest known gemstones that have been appreciated throughout history as an object of ritual, and later as an item of barter and wealth. Today jade is perceived as an object of art and personal adornment.Jade refers to two chemically different stones: jadeite and nephrite. Jadeite jade is more popular in terms of value, while nephrite is known for its carving and antiquity.

What are the colours of jade?
Jadeite comes in six basic colours with many variations. These are green, lavender, red, yellow, white and black. Green is the most important and desirable colour. A special category, imperial jade, was mostly possessed by royalty. Imperial jade possesses an almost transparent, emerald-green colour without visible flaws and colour irregularities.Jade often displays multiple colours within one piece. The Chinese have a list of phrases to describe the colour combinations, such as glassy, icy, old mine, dry green, oily green, and pea green.

What is the best colour?
The most desirable colour is the finest green that resembles the colour of fine emerald. Values in descending order for other colours are lavender, red, yellow, white and black. Overall, quality of colour, clarity, cut, translucence, tone and texture affect the value of jade. There is a perception that jade matures and grows green with age. There is, however, no evidence that jade actually changes colour.

Where does jade come from?
The earliest known jade used by the Chinese (nephrite) probably came from northwest China. Today, Myanmar is perceived as the primary source of high quality jadeite jade. Nephrite, found worldwide, is not a rare stone.

Is jade durable?
Jade is the toughest of all known gemstones. What other stone can be fashioned from a single piece of material and endure as jewellery for centuries?

Is jade expensive?
While most coloured stones are sold by carat weight, jade is sold by the piece. Fine cabochons, bangles, carvings, discs and other popular forms of jade jewellery can command high prices. Nephrite by contrast is less valuable.

What about imitations?
Jade may be treated to improve colour or clarity. The common classification for jadeite jade includes: A jade (waxed); B jade (bleached and polymer impregnated); C jade (dyed). Treated jade may display good colour and transparency but its beauty may not last long. There are many natural minerals such as aventurine quartz, soapstone, serpentine and maw-sit-sit that resemble jade. Common imitations are man-made green glass, plastic and assembled stones. As always, if in doubt, consult a reputed gem testing laboratory.

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