Perylene green (PBk31)
Is it green or is it black, hard to say. Maybe it’s a black color with a green tone. If you paint with the color concentrated, it is clearly black, but if you dilute it a little with water, it turns green. The color index name for the pigment is PBk31 (Bk stands for black) that says something about hue.
For being such a dark color, it is remarkable that it loses so little value when it dries. It turns beautiful gray with any cold red to violet color. The green tone is slightly yellowish. Perylene green is semi-transparent, quite staining and does not granulate at all.
Try using it for dark shadows in foliage, or diluted for glazing shadows in a portrait. One of my students, on a course in Tuscany, called the color cypress green, it is perfect for Tuscan cypresses in the distance.
It is not a color that you “must” have, it does not add much to your palette. But once you get it, there is a risk that you will use it all the time, and that’s nice.
Color index: PBk31
Lightfastness : Excellent
Transparency: Only semi-transparent
Staining: Yes, but not very much