Preheat oven to 400°.
Sift together dry ingredients. Using 2 forks or a pastry blender, cut in butter to coat pieces with flour. The mixture should look like coarse crumbs.
Gently fold blueberries into batter. To avoid greenish-blue scones, do not mash or bruise blueberries. Make a well in center and pour in heavy cream. Gently fold everything together to just incorporate; do not overwork the dough.
Press dough out onto lightly floured surface, into a rectangle about 12 x 3 x 1 1/4 inches. Cut rectangle in half, then cut pieces in half again, resulting in 4 (3-inch) squares. Cut squares in half on diagonal to form triangle shapes.
Place scones on ungreased cookie sheet and brush tops with a little heavy cream. Bake for 15 to 20 minutes until golden brown. Let scones cool slightly before serving.