Cutter must adjust the rough area carefully, to take the gray, blue and colorless out of its trichroism.
刀具必须调整粗糙地区认真，采取灰色，蓝色和无色出其。
2
Trichroism . As of now, no such treatment has been used successfully to lessen or remove color, that is why you can always be sure that they are not treated.