2 different recipes. Brands sell different pigment mixtures under this name, so they won't all look or mix alike. Compare the pigments below.
Who makes it
PB29 Ultramarine Blue1
- Holbein Artists' Oil Color No. H370
PB29 Ultramarine Blue + PBk9 Ivory / Bone Black1
- Daler-Rowney Georgian (student)Student No. D111014133
Sizes are the ones each line is sold in; marks a size only some colors come in. Check the store for a particular color.