Combine the flour, sugar, baking powder, salt, and baking soda in a large bowl and stir with a whisk to blend. Add the butter and cut it into the flour mixture with a pastry cutter to the size of peas. Gradually add the buttermilk to the dough, mixing with your hands until the dough just comes together. Gently mix in the fruit with your hands. If the fruit is juicy, less buttermilk can be used. Do not overmix, or the scones will be tough.
Turn the dough out onto a lightly floured work surface. Divide the dough in half and form each piece into a disk 2 inches thick. Use a knife to cut each disk into 6 even triangles. Line a baking sheet with parchment paper. Place the scones 2 inches apart on the prepared pan and refrigerate for 30 minutes.
Preheat the oven to 375° F. Using a fork or small whisk, beat the egg and cream together in a small bowl. Using a pastry brush, coat the top of each scone with the egg mixture. Sprinkle with the turbinado sugar and bake for 20 to 25 minutes, until a light golden brown. Remove from the oven and transfer the scones to wire racks. Serve warm or at room temperature.Servings: about 12 scones