In a large bowl, sift together the flour, salt, baking powder and sugar. Cut the butter into the dry mixture with a pastry cutter or incorporate with your fingers until the butter pieces are pea-size.
In another large bowl, whisk together 1 egg, the egg yolk, vanilla, heavy cream and buttermilk. Use a large spatula to fold the wet ingredients into the dry just until a dough begins to form. Mix in the cherries and form the dough into two 5-inch rounds, wrapping each tightly in plastic wrap. Refrigerate for 1 hour.
In a small bowl, whisk together the remaining egg with the 2 tablespoons of water. Preheat the oven to 400°. Cut each round into 8 equal, triangle-shaped pieces. Place the scones on a lightly oiled baking sheet, brush each one with the egg wash and bake for about 15 minutes until browned and cooked through. Transfer the scones to a cooling rack and serve warm or at room temperature.
