Sometimes an image explains things faster than words. How can you tell when your fruit pie is ready to come out of the oven? When it looks like this (which happens to be blueberry, baked for my dad's birthday).

The crust is half rye flour and half all-purpose flour, which accounts partly for the darker color. I also use butter or lard every time I can, and they brown better than crusts made with vegetable shortening (which a lot of the bakers I know here in Southeast Ohio use exclusively; I feel it results in a pasty, wan crust, but I will still gladly eat their pies).