Preheat the oven to 400°F. Line a baking sheet with parchment paper or nonstick baking mat.
In a large mixing bowl, combine the flour, granulated sugar, baking powder, salt, and baking soda.
Grate the butter into the dry ingredients or cut in using a pastry blender or two knives.
Separate the eggs and set aside the whites. Beat the yolks with the milk and pour into the dry ingredients. Mix with a spatula until just combined (it will be sticky). Fold in the blueberries.
Flour a work surface and scoop out the scone dough. Knead a few times, adding just enough flour to prevent sticking.
Pat dough into a circle about 8 inches in diameter. Cut into 8 wedges. Transfer to the lined baking sheet and brush with the reserved egg white (you will not use it all). If desired, sprinkle scones with sparkling sugar.
Bake for 15-18 minutes, until golden brown. Let cool briefly and serve.