The color of night sky or shadows, very dark, reddish, semi-opaque blue with strong tinting, also known as Indanthrone. A versatile alternative to Ultramarine yet not as overpowering as Phthalo. (Series 7) 

Pigment Classification: Organic
Color Index Name: PB60
Color Index Number: 69800
Chemical Description: Indanthrone
Opacity/Transparency: Semi-Transparent
Lightfastness Rating: ASTM 1
Permanency: Excellent