can you clarify? You could remove the mantle completely and stone the façade all the way up, wrapping the sides til you hit the edge of the bookcase. Or just wrap the corner and then stop, leaving the side wall of the chimney painted til it meets the edge of bookcase.

the wrap around idea will not look right with the already installed "bookcase'. It could go just around the corner…but what kind of finish are you then thinking of ? the stonewall has a square edge…..

Your stone should have some kind of coordinating edge piece that is L- shaped. It would be placed in the same pattern as the rest of the stone, but it will wrap the corner and then stop. If you look at the stone from the side, you would just see a neat vertical edge going up and down, maybe 2-3 inches wide. I guess that can be determined by the stone you use. Do you have any pictures of your material?

You can look through these to get an idea. http://www.houzz.com/stoned-wrapped-fireplace there is bound to be some scenario similar to what you are doing. You will see the corner pieces as well.

I would change out the mantle to a clean-lined rectangular box mantle spanning the front of the fireplace. If you google "box fireplace mantle" there are many images to look at from rustic to formal. As for the stone surround, how thick is the stone? Some manufactured stone is quite thin and you might be able to run it back to the built-ins without it blocking the cabinet doors. If not you have 2 options. As said before, stone the front and wrap the corner with the "L" shaped stone piece, or just stone the front of the fireplace. I have seen it done both ways.

Thank you all I have got some good Ideas how to go about it and will come back soon with either more ideas or a decision. At least I have had some great input ;)

the stone is 2 cm…