You can paint your fireplace with oil-based paint or water-based paint, but the most important is to use sub-layer is provided for stone and brick. You should first clean up to prepare the surface. You can clean brick or stone with alkali St Marc and the time it takes to dry before applying two layers of paint. Do not forget to protect the wall around the fireplace with masking tape before applying undercoat.
Regarding the choice of colors, have a look at what underlies give as given: if white plays according to the lean side of your home, stay in the shade, if not you want to emphasize the design of the fireplace, you can refer you to a taupe color is already present in your home.
Enjoy underlayment to allow you time to think, sometimes, especially when you can, it’s good to see and feel things before you decide!