Preheat oven to 425°F and position rack in lower third of oven.
In a large bowl, mix together the granulated sugar, flour, cinnamon and cloves.
Add in the rhubarb and toss of coat. Spoon onto a 9-inch pie crust lined pie plate.
Dot with butter. Cut the second piece of pie crust into ten 1 inch stripes and weave into a lattice. You can also just simply place the pie crust on top and cut a few slits for ventilation. Press and crimp the edges.
Whisk the egg and water together in a small bowl. Brush over the top of the pie and sprinkle with coarse sugar.
Place the pie on a baking sheet and bake for 15 minutes at 425°F. Then lower oven temperature to 375°F and continue baking for another 30 minutes or until the crust is golden and filling is bubbling. If the crust turns golden before the filling is done, loosely cover with foil to prevent over browning. I covered my pie during the last 10 minutes. Let cool for 1 hour before serving.