Stone fireplaces add something to any room, and there are many styles to fit any decor. The first example is a simpler style, one profile for the surround, and another for the mantle. Many fireplaces will also have a flat hearth stone under the fireplace as well.
The next example is a bit more complex, with column-like legs and flat panels, with a curved top and both mantle above and a hearth below.
Next is another clean design style, basic profile and mantle, but this one adds a tall upper mantle.
The next design adds several levels of detail. The basic profile, mantle, legs, and curved top of the firebox (this time with a gothic style curve) have increased lines of definition, and the flat panels have lines as well.