Black has stable, grave, classical, charm, noble, mystery, represents the low-key, implicative and restrained trait. 

Black agate
Appearance features: color gray green, blue ribbon pattern, contains more impurity. Some head is better, for the translucent.
Diamonds are the existing materials thermal conductivity in the fastest, if your CPU has a diamond do radiator, then... You must have been mad natural material, diamond is the hardest, but theoretical calculated that CN3 than diamond to hard, it is a pity.
Flash ShiYu

Appearance features: head foot, translucent above. Grease to vitreous luster. Green is uniform. Pole and high-grade jade interblend.

Siliceous rock jade
Calcium aluminum garnet ShiYu
Appearance features: head is poorer, slightly transparent to translucent. Green is mottled or banded. Hardness and feel similar with jade.

The most common on the market a fake jade jade. The personage inside course of study known as "water foam jade".
Sodium long ShiYu