In a large bowl, mix together flour, sugar, baking soda, baking powder, and salt. 

With a pastry cutter, cut in butter until it resembles fine breadcrumbs. Make a well in the center of the ingredients. 

Add blueberries, lemon zest, buttermilk, and vanilla into the center of the well. Gently combine until the ingredients are combined and wet, being careful to not overwork or pop the blueberries. 

Turn dough out onto a floured surface and pat into a disk about 1 1/2 inches thick. Cut into 12 triangles. Place the scones on a parchment-lined baking sheet and chill for 30 minutes. 

While the dough is chilling, preheat the oven to 400°. Brush the tops of the scones with heavy cream and sprinkle with sugar. 

Bake for 12 minutes or until lightly browned. Transfer to a rack to cool. 

To make the glaze, whisk powdered sugar, lemon juice, and vanilla until smooth. Add more water or powdered sugar as needed to get the right consistency for glazing. 

Drizzle lemon glaze over cooled scones and serve.