This lenses will change the color permanently under the sun,but the original color will not change.it has high index and good optical capability.the color will change according to strong or ebb light outside.the color changing time and fading time is very short. and this lenses are hard,durable,not easy to scratch,stable physical and chemical character,not easy to be cankered,good ability of brave ultraviolet. Especially the color of each piece is same, so it is very easy to adapt one pairs of this lenses or change any piece.