In a medium saucepan, combine the blueberries with the Simple Syrup and lemon juice. Cook over moderately high heat until the berry skins darken, 1 to 2 minutes. Drain the berries, reserving the syrup. In a pitcher, combine the berries, half the syrup and all of the remaining ingredients except the lavender sprigs. Cover and refrigerate until chilled. Stir and strain into 6 chilled martini glasses. Garnish with the lavender sprigs.