Phthalo Blue (Red Shade)Copper Phthalocyanine Blue. Very clean transparent pigment with a red undertone. An organic carbon based pigment which is an extremely fine particle size. Be careful not to drop this jar or you will be vacuming up dust for weeks and weeks throughout your studio. Excellent for glazes and washes. PB 15:1 Color Index Number 74250Lightfastness I (Excellent)