Preheat oven to 425°F (220°C). Sift together all-purpose flour, baking powder, baking soda, sugar, and salt into a large bowl.
Cut cold butter into flour mix until it resembles coarse breadcrumbs.
Add blueberries and half-and-half or milk. Mix with a spatula until a sticky dough forms.
Turn onto a lightly floured surface and pat out to ¾ inch thickness. Cut dough with 2-inch fluted round cutter.
Gather the scraps together, reshape, pat it out to ¾ inch thickness, and cut with 2-inch fluted round cutter until all dough is used up. You should get 12 to 14 scones.
Bake in preheated oven for 20 minutes or until golden brown.