Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a medium bowl, whisk together the flour, baking soda, cream of tartar, and salt.
In a large bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy.
Beat in the eggs one at a time, then stir in the vanilla extract.
Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Gently fold in the diced peaches.
In a small bowl, mix the cinnamon and 1/4 cup of granulated sugar.
Scoop tablespoon-sized portions of dough, roll them into balls, and then roll each ball in the cinnamon-sugar mixture.
Place the coated dough balls on the prepared baking sheet, spacing them about 2 inches apart.
Bake for 10-12 minutes, or until the edges are lightly golden.
Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.