Exposed crystals are crystals transformed from the jade itself due to physical factors such as heat and pressure. They are sometimes called micas. Almost all the antique jades buried underground have shown exposed crystals. One postulate of the exposed crystals of antique jades is that the inner force of jade elements of jade carving has been changed from the inner force of jade elements of raw jade stone. Exposed crystal is caused by the changing shape and arrangement in the whole structure of jade due to the heat and pressure forces.