Preheat oven to 425°.
In a large mixing bowl, combine flour, sugar, baking powder, baking soda and salt. Cut the butter into small cubes and use a pastry cutter or fork to combine it into the flour. Add buttermilk, orange zest, and raisins and use a spatula or spoon to combine until all the flour is moist.
Dust a surface and your hands with flour and gather the dough onto the surface. Knead about 5 times and then shape the dough into a ball. Use a rolling pin to flatten to about a half inch to an inch. Then, use a knife or pizza cutter to cut into 8 or 10 pieces, depending on how large you'd like your scones.
Line a baking sheet with parchment paper and place the scones on the baking sheet, leaving ample space between them. Whisk the egg (optional: add a splash of milk) and brush the scones to create a glaze. Sprinkle with granulated sugar for texture.
Bake the scones for about 14 minutes or until the are just golden brown.
Serve warm with butter, jam or honey.