1. Combine sugar and 3/4 cup water in a small saucepan; bring to a boil. Cook 2 minutes, stirring until sugar dissolves. Cool to room temperature.
2. Combine remaining 1 1/4 cups water and raspberries in a blender; pulse 10 times or until well blended. Strain mixture through a fine sieve into a large pitcher; discard solids. Add orange juice, lemon juice, sparkling water, and cooled syrup to pitcher; stir to combine. Serve immediately over ice.