Do remember carrying jade flashlight and scale when buying jade.
Bring one or two small material scale that you think you can accept the whiteness of fabric and you need to buy the material of the white degree were compared.
If you always see a bunch of very not white material, inside the white one you will see more and more white, in the absence of scale the last impulse buy back,and regret whem back home.
According to flashlight  you can look at the internal characteristics the jade for perceptible, Yin crack, crack about deep.According to jade flashlight irradiation we can see hetian jade material have to lorraine, it jade texture, waterline, black spots impurities, etc.
Warm reminder: the best time to see the jade is at 10:30 in the morning to see jade points around the sun.