The intensity of Cat's Eye can vary from strong to weak. The clarity and intensity of the cat's eye band will play an important role in the value of a Cat's Eye gemstone. A bright and straight light effect is the most desired, and when strong and perfect it will be highly valued. In some forms of Chrysoberyl, the cat's eye effect is weak, appearing only as a billowy, floating light reflection as opposed to a bright, concentrated band of light. Such Chrysoberyl is known as Cymophane, and the effect is called cymophane effect. - See more at: