In a quart jar, blueberries, 1 cup sugar, and vodka. (I use frozen blueberries as the freezing process breaks down the cell walls, allowing you to get more juice).
Seal jar tightly, and place in a dry, dark place for about 2 weeks.
After two weeks, strain the liquid using a double layer of cheese cloth. Gently squeeze the blueberries, getting as much juice from them as possible.
In a fresh quart jar, add the second cup of sugar, water to top and the strained liquid. Seal and store again in a dark place until sugar is dissolved.
Once the sugar has all dissolved, bottle the resulting liqueur in a fresh bottle and let age for roughly 3 months.