Some fast facts
Jade is a family of minerals made of two distinct branches with different properties but sometimes with a close appearance: jadeite and nephrite. Jade builds up under high pressure (10.000 atmospheres) but at rather low temperature for a mineral (200-300 degrees).
It is the French gemologist Alexis Damour who identified during studies in 1846 and 1863 two types of jade: one under the amphibole group, he has named it nephrite, and another one, a sodium-aluminum silicate belonging to the pyroxene group named jadeite.
These two minerals are then aggregates.
Their physical properties are also different: nephrite has a hardness of 6-6.5 on the Mohs scale while jadeite has 6.5-7. Their density is also different: 2.9-3.03 for nephrite and 3.3-3.38 for jadeite.
So Jadeite is harder and ten percent heavier than nephrite.
While being of medium hardness, these two minerals are very strong (they do not break easily) that’s why they can be carved with high precision. Because nephrite is fibrous it is stronger than jadeite but has often an oily appearance, jadeite grainier can be polished like a mirror.
Jadeite jade exist in any color without exception, but nephrite jade has a limited range of colors.
Jadeite jade is found in Central America, Russia, Japan and some other countries but the only jadeite heavily commercialized, worldwide renowned and highly prized is Burmese (Myanmar).
Common questions with their answers:
What is imperial jade?
It is transparent emerald color jadeite. Some sellers call imperial jade any color transparent jade, it is a mistake. Its intense green color is mainly due to chromium.
Does fake jade exist?
Not really. There is nephrite or jadeite and treated jade. No synthetic jade has ever been produced. Plastics and glass can sometime try to fake jade but they are easy to recognize. Some other stones can sometime be misleading: serpentine, moss quartz, aventurine, chrysoprase, saussurite…
What is Chinese jade?
Nephrite. There is no jadeite jade mine in China, only nephrite. Nephrite is quite common in China, most of the huge dark green carvings you can see in Chinese shops are nephrite jade. Nevertheless China is the prime importer of Burmese jadeite.
What is treated jade?
Nephrite is never treated, it is too cheap to be treated. For jadeite it is another story… treated Jadeite is often found in Asia and all around the globe, very low prices are often an indication. There are many types of treatments:
- Jadeite is ‘cleaned’ in acids baths, loosing most of its surface impurities and eventually bad colors, opening also veils and cracks. Then it is plunged into resin to fill those cracks, hardening the stone and polished. This jade is called ‘B’ jade on the market.
- Jadeite who is simply colored without adding resin is called ‘C’ jade.
- Jadeite who is colored and filled with resin is ‘B+C’ jade.
- untreated jade is called ‘A’ jade.
- Jadeite is often waxed to ease its polishing stage and make it glossier. Has long as the quantity of wax in the jade is reasonable the jade is considered as ‘not treated’. Most of specialized gem labs care about the amount of wax present in the tested stones, not all gem labs… so be careful with lab report tests.
How to detect treatments?
With a lot of experience and a good loupe! It will directly depend on the quality of the treatment. A ‘well done’ treatment B or B+C is hard to detect ‘naked eye’, only an infrared spectrometer used by big gem labs will be able to detect it. Type ‘C’ jade is easier to spot as coloring ink appears in cracks. Expensive jade should always be sold with an appropriate gem lab report: no excuse.
How to appraise jadeite?
It a lifetime work! A book can be written on that subject only! Lavender jade is famous, but the rarest color in jade is blue. Still the most expensive is definitely imperial jade. Translucency is as important as color. For carved jadeite, the quality of the carving and its meaning is also very important…