In a large pitcher, combine the fresh lime juice, orange juice, grenadine syrup, simple syrup, and pineapple juice. Stir well to combine.
Pour in the dark rum and mix thoroughly.
Stir in the grated nutmeg and ground cinnamon. Adjust the sweetness with additional simple syrup if needed.
Refrigerate the mixture for at least 1 hour to chill and allow the flavors to meld.
Fill glasses with ice cubes and pour the rum punch over the ice.
Garnish with orange slices and maraschino cherries.
Enjoy your meal!