I have struggled to find a good blue black before, winsor and newton make one which is passable but a long way from handmade high pigment paint. This is the best choice I have used, historically accurate as well.
Rublev- "Blue Black appears in the catalogues of artists’ colourmen circulated in the nineteenth century. Some references describe it as charcoal black, which may have been derived from charred vine cuttings or wood charcoal. It is often listed as a mixture of 40 parts bone black and three parts Prussian blue, which is the composition of Rublev Blue Black."
|Colour Index:||Pigment Black 9 (77267)|
|Chemical Name:||Hydroxyapatite (calcium phosphate) and carbon|
|Chemical Formula:||Ca5(OH)(PO4)3 and C|
|Colour Index:||Pigment Blue 27|
|Chemical Name:||Ferric ferrocyanide|
|ASTM Lightfastness:||Not rated|
|Tinting Strength:||Above Average|