DDJD,You want to buy 100% castor oil, not Jamaican black castor oil.
It's clear and a pale yellow color.
Food/Pharma grade (USP or BP) is ideal as it ensures a high enough standardization of Ricinoleic acid.
Ricinoleic acid is the component of castor oil that boosts PGE2 and we care about.
I read that PGE2 is pro-inflammatory. Why do we want to increase it?