Paint the inside of the fireplace black, you won't find any other color that is heat resistant.

We need more context to answer the rest. Post a picture of the fireplace taken from the other end of the room so we can see the fireplace wall as well as some pictures of the room and decor. Include a picture of the marble.

With that said, maybe these will helpt:

Marble only, with Framed Curtain Screen

Marble with Fireplace Glass Door and matching Steel Mantel Shelf

Marble floor to ceiling with Framed Curtain Screen.

Mockups By: Fireplace Treatments

The window picture is the wall opposite the wall with the fireplace. I think this is the correct picture of the marble or pretty close to it. I took so many pictures at the stone yard of a variety of marbles!

I was hoping I might be able to create a better mockup for you, which is why I asked for the pictures. Can you please take the same pictures but without the wide angle view that is causing them to be drastically curved?

We're still in the process of redoing the entire room. The floors will be redone most likely to the same color to match the rest of the house. The coffee table will be replaced with an updated style. The other hard surfaces should be staying. The couches are new. We haven't hung any pictures. Thanks for all your help.