Brian in DC's Profile

Simple Solution: make a Wall to Wall wooden 3 sided U-shaped cover that is 6in high or bigger that would slide over top of the existing mantle/stone supports. Stain it a nice contrasting Warm Antiqued brown or Chocolate brown color.

Paint the walls a color that contrasts the stone (its too neutral) and upgrading the fan to a nicer one (or a Chandelier) would also help create the Cleaner style your going for.

Other Solution: Consider adding small built-in cabinets on top of the hearth on either side of the fireplace (this could hide your TV, store Firewood, Books, etc) and let some of the stone remain uncovered around the edge of the fireplace so it relates to the stone above/below. Connect the built-ins with a thick wall to wall mantle.

Just some thoughts that could help you save $$ and wouldn't be as messy/pain staking as removing or painting over the stone.