Place 2 cups water, sugar, and preserves in the container of a blender. Process 30 seconds. Strain through a fine-mesh strainer. Place mixture in a large pitcher. Stir in lemon juice and chill.
Just before serving, stir in ginger beer and seltzer water. Serve over ice. Garnish with lemon and blackberries, if desired.
Notes
*We used Bonne Maman Blackberry Preserves and Fever-Tree Ginger Beer.
Recipe by Southern Lady Magazine at https://southernladymagazine.com/sparkling-blackberry-ginger-lemonade/