Combine the watermelon juice, lemon juice, and pectin in a large pot.

Whisk the pectin in and bring the mixture to a rolling boil over medium high heat.

Stir in the sugar.

Bring the mixture to a boil, stirring continually. Boil 2 minutes.

Remove it from the heat.

Test to make sure the jelly is set (as seen in the video.) If the jelly is set, jar as below. If it is still runny, return it to the heat and boil for another minute. Test again.

Ladle the jelly into hot, half-pint jars. Leave 1/4 inch head space.

Wipe the rims of the jar with a damp rag that has been dipped in white vinegar. This ensures that there is no residue, and your lids can seal properly.

Close with lids and rings.

Process the jars in a hot water bath canner or steam canner for 10 minutes.

Allow the jars to cool in a draft-free location for 12-24 hours.

Remove the rings, test the seals and label the jars.

Enjoy!