You could try out different paints with this https://www.sherwin-williams.com/visualizer/

You are painting the diamond piece thingy below, correct?

Yes, I'm painting the whole thing. The bottom is just a color that I tried, and I didn't like it. It is a copper color. I wonder if the small area above the fireplace should be a different color? Everything you see is small square tiles.

can you add your favourites from the Sherwin Williams visualiser ?! (screen dump ?! ) so we can vote by adding likes ?!

you might look at some slate greys to go with the dark aqua, with the white it would be quite pretty

What do you mean, Sheryl?

slate grey on the bottom piece of the fireplace and you said previously you want to add dark aqua with the white mantle

- @thinkwhite, how extensive is the "fireplace update" project in your mind? Are you really just thinking about paint? It might need something a little more radical to help ease up the odd proportions . . .

I painted the whole thing white.

There are some really great fireplace photos,online where the fireplace sits in the middle,of the wall, no mantle. They look fabulous and clean.

The white side walls are intruding onto the other walls... Check this out.... Would you consider a build out to the ceiling above the mantle on the side walls. ... be faux or functional. Small book cases maybe, or a framed partition, but you have continuity of the space.
http://www.roomzaar.com/rate-my-space/Living-Rooms/Fireplace-Makeover/detail.esi?oid=6532456