While many gemstone rocks are referred to as jade, when we refer to Jade we are talking about either Nephrite Jade or Jadeite.
Both Nephrite Jade and Jadeite are similar in that they possess a microcrystaline structure which under magnification appears to be elongated, interlocked and layered. It is this structure that gives Jade its strength and toughness. It also enables Jade to be carved into intricate shapes and carry a high polish.
Superficially Nephrite Jade and Jadeite may appear similar. In their raw state they look like rough rock with a rind-like exterior camouflaging the gem quality stone within. Chemically the two forms of Jade differ slightly.
Nephrite Jade is slightly softer than Jadeite, with Nephrite being 6-6.5 on the MOH scale, and Jadeite being 6.5 - 7. This slight difference means Jadeite is more likely to carve and hold complex, detailed shapes, however in daily use it makes little difference. Where MOH scale is important is that only another gemstone with a higher MOHs will scratch the surface of Nephrite or Jadeite, such as diamond, sapphire, ruby or quartz. In some instances the scratch test can help eliminate softer, similar in appearance stone such as serpentine from Nephrite Jade. We don't recommend using this test on finished carved products. Shown above is a spoon carved by Donn Salt from Nephrite Jade sourced from Aotearoa/New Zealand.
Jadeite will appear slightly heavier than Nephrite Jade, though again the difference can be difficult to detect. Jadeite has as specific density of 3.3-3.8. Nephrite Jade has a specific density of 2.9 - 3.03. Both Nephrite and Jadeite will appear highly translucent when held to a light source. This image shows a Chinese cabbage, complete with insects, carved from a multi-coloured piece of Jadeite. Image courtesy of National Palace Museum.
When handling either Nephrite Jade or Jadeite the stone will feel waxy and smooth, almost greasy to touch. Even when highly polished this appearance will be maintained.
Colour can be confusing. To the untrained eye all Jade can appear to be green. In reality, both Nephrite and Jadeite are found in a wide variety of colours, including black, blue, white, brown, lavender and orange. There can be regional colours that enable enthusiasts to identify the source of Jade. Even the green theme ranges from light cloudy green to bright emerald green to deep, dark green.
Jade can appear cool or cold to hold compared to manufactured items and other gemstones. Jade will heat up when exposed to direct sunlight for a prolonged period however it will cool down quickly.
When purchasing Jade items the safest way is to purchase from an authentic retailer who is transparent about the source and quality of their Jade. They should offer a guarantee of quality and allow for you to return an item should you have any concerns. You can purchase genuine Jade jewellery from markets. Outside of Asia there is less risk of fake Jade and the resellers are often makers or artists. Be prepared to ask questions as to the source of Jade, pick up the item, feel the weight in your hand, hold it up to the light and if you like it then buy it. If anything makes you feel uncomfortable then put it back upon the shelf. If you want to think about it, take time to check out the resellers social media and website.
Jadeite is rarer than Nephrite. You should expect to pay more for Jadeite items of a similar design to that created from Nephrite.
As with all gemstones and jewellery there is nothing wrong with buying fake Jade or Jade that has been treated so long as you made the purchase fully aware of what it is you are buying.
Featured image shows boulders of Jadeite and Nephrite Jade held by the British Museum