In a large bowl, whisk together the sugar, flour (or other thickener of choice) and cinnamon.
Add the blueberries, lemon juice, and melted butter. Carefully mix to fully coat the berries, being careful not to break them (a couple is fine, you just don't want a pie full of crushed berries!).
Remove the crust from the fridge and with a fork, dot the bottom with holes. Scoop the filling into the pie dish.
Roll out the bottom crust to the same thickness as the bottom crust. Don't worry, it won't be as large. Carefully cut into 3/4" thin strips and place into a lattice over the pie filling. Alternatively, you can just place the top crust on. Trim off any excess dough, and crimp the edges together with your fingers or a fork. If you're not making a lattice, make sure to cut some slashes in the top dough to allow steam out! Sprinkle the dough with the coarse sugar or cinnamon sugar.
Bake the pie for 15 minutes at 425°F, then reduce the temperature to 350°F and bake for another 40-50 minutes. Watch carefully, and if the edges start to get too brown, cover them with tinfoil. The pie will be done with the crust is golden brown, and the blueberries are bubbling.
Remove the pie from the oven and allow to cool for at least 1 hour before serving.
Enjoy!