Pour orange juice through a fine-mesh sieve into a liquid measuring cup; discard pulp. Measure exactly 2 cups juice, adding water if necessary. Transfer the 2 cups juice to a 6- to 8-quart heavy pot. Pour lemon juice through the sieve into pot; discard pulp. Stir the 2/3 cup water and pectin into juice mixture.
Split vanilla bean in half lengthwise. Using the tip of a paring knife, scrape out the tiny seeds. Add vanilla seeds to juice mixture, whisking to distribute seeds evenly.
Bring mixture to a full rolling boil, stirring constantly. Stir in sugar. Return to a full rolling boil, stirring constantly. Boil hard for 1 minute, stirring constantly. Remove from heat. Quickly skim off foam with a metal spoon.
Ladle hot jelly into hot sterilized half-pint canning jars, leaving a 1/4-inch headspace. Wipe jar rims; adjust lids and screw bands.
Process filled jars in a boiling-water canner for 5 minutes (start timing when water returns to boiling). Remove jars from canner; cool on wire racks. Makes 4 half-pints.