Jade is a generic name given to two types of minerals, jadeite and nephrite. This gemstone has been known to man for over 7000 years, known as ‘yu’ in China, the Royal gem. It was not until 1863 that nephrite was recognised as a separate type of jade. Most of us would most likely associate the origins of jade to China, due to the demand for it. Jade was, however, often imported from elsewhere, such as Central Asia and then later, Burma; Guatemala was also an important source. Jade was highly prized by the Aztecs and Mayans who named the stone “piedra de hijada”, derived from the Spanish word meaning “stone for the pain in the side”. It is believed that jade can prevent or even cure complaints of the hips and kidneys.
Nephrite v’s Jadeite?
Jadeite and nephrite are very similar in appearance, which is probably why they were not identified as being separate minerals till the late 19th Century.
Jadeite and nephrite are both metamorphic rocks with differing silicate minerals. When tested, subtle differences – such as jadeite being harder and more scratch resistant than nephrite – can be found. Jadeite has a higher density than nephrite also, making it slightly heavier and tougher.
Jadeite is rarer than nephrite, and comes in a variety of colours from different hues of green, lilac, white, pink, brown, red, blue, black, orange, and yellow. The most prized colour is a rich emerald green known as Imperial Jade.
Nephrite is found in many different varieties of green, and even through to a creamy white colour known as “mutton fat” jade.
The most prized of these minerals are those with good, strong, even colour. Examples found with blotches or banding veins running through them can often be just as desirable, provided that their pattern is interesting enough. The minerals have similar, greasy-to-vitreous lustres. Jade has an excellent toughness, even more tough than diamonds. This means it has a strong interior structure, unlike hardness which relates to the surface properties, or how scratch resistant a mineral can be. Due to the excellent toughness, both Jadeite and Nephrite are ideal for carving, and may be used as tools or weapons.
There are many different treatments used to enhance jade, so knowing which treatments have been used allows us to correctly identify these stones.
This is when the stone has had no treatments except for surface waxing; this can be difficult to detect.
This is when the mineral has been bleached and injected with a polymer resin which enhances the transparency and colour of the stone. This is again difficult to detect. The use of infrared spectroscopy can help detect polymer resins.
This is dyed jade, which may be detected under magnification as any dye will be more concentrated within the veins of the Jade.
B & C Jade
This is a combination of both bleaching and dying. The stone has been impregnated with resin as well as surface staining.
This grading usually refers to doublet. This is when a thinner slice of jade may be backed with plastic or an alternative material.
Caring for Jade
Jade is easy to keep in good condition and can be cleaned in an ultrasonic device if untreated. Be warned, however, if you feel you have a piece of treated Nephrite or Jadeite. If you are unsure, warm soapy water should be sufficient.
Nephrite and jadeite are both fantastic minerals. A variety of cuts and colours can be used in an array of different types of jewellery items. Nephrite and jadeite are very wearable stones with great resilience. The innate toughness lends itself to beautiful carvings and ornaments, which can stand the test of time when cared for correctly.