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
PB36 Cobalt Turquoise / Cerulean1
- Blockx Extra-Fine Oil Colours No. 212663
PB16 Metal-free Phthalo Blue1
- Maimeri Puro Oil Colours No. 350
Sizes are the ones each line is sold in; marks a size only some colors come in. Check the store for a particular color.