Jade, an ornamental stone, comes from two different types of metamorphic rock: nephrite and jadeite. Nephrite typically yields green jade, although a creamy white form is also found in nature. Jadeite yields many more variations in colour, from blue and lavender to pink and emerald green. While jadeite is more valuable and is usually the choice for fine jewellery, nephrite is valued for its carving excellence. If you are hoping to find some nephrite or jadeite in its raw form, there are a few things you'll need to consider.
Consider the geographical source of the rock you're trying to identify. Nephrite deposits have been found in China, New Zealand, Russia, Guatemala, the Swiss Alps and Western Canada, while jadeite can be found in China, Russia, Guatemala and Myanmar (formerly Burma). While you may not be hunting down jade deposits in the foothills of the Alps, if you know the rock you're considering did not come from one of these regions, you can safely assume it is not raw jade.
Identify the rock type. There are three basic types of rocks: igneous, sedimentary and metamorphic. Each type forms in a different way and has its own characteristics. Both nephrite and jadeite are metamorphic rocks, which means they have been subjected to heat and pressure, causing major physical changes, chemical changes or both.
Test the chemical composition of the rock. Both types of jade contain silicate. Since you cannot determine the mineral composition of a rock yourself, you would need to send a sample to a lab for this test, but if you believe you have a high-quality source of jade, the expense will be worth it. If the testing reveals silicate is present in the stone, there is a possibility the stone contains jade.
Examine the rock for any see-through points. Some rocks will have a small area where the inside of the rock is visible. After cleaning your rock, thoroughly examine it to determine if you can see past the outer layer anywhere on the rock. If your rock contains a transparent point, you may be able to determine if it contains jade. If the rock does contain jade, you will see a smooth, nongranular section displayed through the transparent area.
Shine a penlight against the rock's surface. If the rock has no transparent point, try wetting the rock's surface and shining a penlight against it to see if you can illuminate any underlying colour. Place a small metal plate between your eyes and the penlight to eliminate any glare. If light is able to penetrate the rock, you will be able to see what's inside. You're looking for a smooth, nongranular and typically green section of the rock.
Cut the rock with a small sharp knife. As a final step in identifying raw jade, cut a small hole in the stone and polish the inside to determine what lies beneath the surface. If a stone you are considering has been cut for this purpose, have it examined by a professional geologist or rock collector to make sure no artificial coatings have been added and the rock has not been tampered with.