Combine blueberries, water, and sugar in a saucepan. Bring to a boil and simmer on medium heat for 15 minutes. Stir occasionally. Remove from heat and mash berries. Pour liquid through a strainer and collect the juice. Refrigerate until chilled.
Using a wedge of lime, run it along the edge of the glass. Dip glass into sugar.
Fill glass with ice to the top. Pour in 3 tablespoons of the blueberry sauce. Using the back of a spoon pour the Izze Water onto the back of the spoon, into the glass. Fill to an inch or two below the top of the glass. Using the same spoon, top off with prosecco.
Garnish with a sprig of mint, a toothpick full of blueberries and a wedge of lime.