You need to post a picture so we can see the wall in question.

I will as soon as I figure out how.

Ok, here are some photos.

Inspiration, you could just add sturdy timber mantel and timber trim the inlay part etc

That might work. The biggest problem is these are all rough cut quartz rocks and they are very uneven. The mantle that is on there has been mortared to the stones and there is a small ledge for it sit on over the actual fireplace part. I'm not sure how to get the old one off in order to put a thicker one on.