Preheat the oven to 400°F (200°C). Line two baking sheets with parchment paper and set aside. In a large mixing bowl, combine the all-purpose flour, baking powder, salt, and sugar. Mix well. Using a pastry blender, cut in the cold butter until the mixture resembles coarse crumbs. Alternatively, you can use your fingers to rub the cold butter into the dry ingredients until you achieve coarse crumbs with pea-sized clumps of butter within.
Toss in the blueberries until evenly distributed; take care to handle the blueberries gently, as mashing or bruising them can cause their vibrant color to bleed into the dough. In a separate bowl, whisk together the cold heavy cream, vanilla, zest, and eggs until combined. Gradually add the wet mixture to the dry mixture, folding until the dough just comes together. It may be a bit crumbly, but that's perfectly fine. Be careful not to overwork the dough, as this can result in tough scones.
Dump the dough out onto a very well-floured surface. Sprinkle a little more flour over the dough to prevent sticking. Flour your hands and knead gently into a ball. Press the dough into a circle approximately 1 inch thick, adding a little flour as needed to prevent sticking to the working surface.
Cut the circle of scone dough into 12 tringle-shaped pieces using a bench scraper or a long sharp knife. Carefully wiggle the slices to loosen them from the surface, making it easier to lift them. Using a bench scraper or your hands, gently lift each slice and place them onto the prepared baking sheets, leaving some space between each scone. Chill the scones in the freezer for 20 to 25 minutes before baking.
Preheat the oven to 400ºF. Once chilled, lightly brush the tops of the scones with cream and sprinkle with turbinado sugar if desired. Bake the scones for 20 minutes, rotating the pans halfway through, until the tops are lightly browned and the insides are fully baked. Remove the Lemon Blueberry scones from the oven and allow them to cool for 15 minutes on the cookie sheet, then transfer them to a cooling rack to cool completely.