Place oil in a tall container and then freeze for 1-2 hours. You want the oil to be liquid still but as cold as it can be.
Once the oil is cold, get the grapefruit juice and agar agar in a pot and bring to a boil for 1-2 minutes.
Then while this mixture is still warm, use a squeeze bottle or syringe to stream the grapefruit mixture into the cold oil.
It will split and harden into little pearls. Strain the pearls out from the oil then rinse the pearls in cold water.
Serve on appetizers, desserts or as garnish. Store in the refrigerator.