Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper.
In a large bowl, whisk together the flour, granulated sugar, baking powder, baking soda, salt, and orange zest.
Add the cold butter cubes to the flour mixture. Use a pastry blender or your fingertips to cut the butter in until the mixture resembles coarse crumbs with some pea-sized pieces remaining.
Stir in the chopped cranberries until they are evenly distributed.
Pour in the cold buttermilk. Use a fork to mix until a shaggy, slightly sticky dough forms. Do not overmix.
Turn the dough out onto a lightly floured surface. Gently pat the dough into a 1-inch thick circle, about 8 inches in diameter.
Using a large knife or bench scraper, cut the circle into 8 equal wedges.
Place the wedges on the prepared baking sheet, leaving about an inch of space between them.
Brush the tops of the scones with melted butter and sprinkle generously with coarse sugar.
Bake for 18 to 20 minutes, or until the tops are golden brown. Let the scones cool on the baking sheet for a few minutes before transferring to a wire rack.