In a bowl whisk together 1/2 cup of the buttermilk, the egg, the brown sugar, and the vanilla until the mixture is combined well.
In another bowl stir together the flour, the baking powder, the baking soda, and the salt and blend in the butter until the mixture resembles coarse meal.
Stir in the cherries and the buttermilk mixture with a fork until the mixture just forms a sticky but manageable dough.
Knead the dough gently for 30 seconds on a lightly floured surface, pat it into a 3/4-inch-thick round, and cut it into 8 wedges. On an ungreased baking sheet brush the wedges with the remaining 1/4 cup buttermilk and sprinkle them with the granulated sugar.
Bake the scones in the middle of a preheated 400°F oven for 15 to 18 minutes, or until they are golden.