Though most people think of jade as being green, it can be found in many other colours, including nearly black or bluish white. Jade can be made either of the mineral nephrite, which is a soft rock and prized in China, or the mineral jadeite, which is hard and more rare. The quality of jade is determined by its colour, tone, translucency and texture, and the skill with which it's been cut. If you're interested in starting a collection, being able to identify genuine jade is essential.
Check for air bubbles. If there are any, it's treated glass, not jade.
Put the jade in your hand. Jade is dense, so should be heavier than glass and most other rocks of similar size.
Scratch the rock with a steel scrubber. Jade doesn't scratch.
Wrap a strand of hair tightly around the jade. Hold a flame to the hair. If the hair burns, the rock is not jade; jade would have absorbed the heat.
Touch the jade to your cheek. Jade should feel cool in most environments.
Hold the jade in one hand and hit it with a rock using the other. Jade should make a resounding sound.
Run your fingernail along the stone. If it's bumpy, it's probably not jade.
Try chipping or breaking it. Jade is extremely durable so it shouldn't chip or break easily.