Make blueberry syrup. Bring water, sugar, blueberries and ginger to a slow boil until sugar is dissolved, stirring and smashing berries. Turn heat down and simmer on low for 5 minutes. Strain into a small bowl and chill in the fridge for 20 minutes.
Mix syrup, grapefruit juice and vodka together with 1 cup of ice in a large stoneware pitcher, stir to combine. Top with sparkling wine.
Fill each glass with ice, a strip of grapefruit zest and a few blueberries, then pour sparkling cocktail over ice into each glass.