4 cups unsweetened blackberry juice
2 1/2 cups white sugar
10 whole cloves
1/2 cinnamon stick
1 lemon, zested
4 cups rum
Combine blackberry juice, sugar, cloves, cinnamon stick, and lemon zest in a large saucepan. Slowly bring to a boil, stirring until sugar dissolves, about 5 minutes. Remove from heat and allow to cool.
Strain to remove spices and add rum.
Pour liqueur into a sterilized bottle and seal. Store in a cool, dark place.