Maybe do moulding like this? So that the moulding hugs the stone instead of laying completely on top of it?

BTW what is the wood you used on your floor and color? It's beautiful!

That's what I was thinking but I think there will be gaps underneath between the molding and the stone

A fine carpenter can do it for you easily! Just make sure you get a good one! :)
They can caulk any gaps especially since you are painting it white!

Thanks for the floor compliment!

They are ebony stained oak floors with a satin finish. We had them refinished and they turned out amazing.

Hi Ken,
An accomplished finish carpenter will be able to create a scribed molding to be attached behind the bottom-most contact point of the crown. If you prefer to DIY, then purchase a 3/4"x1 1/2" length of poplar. Have a helper hold the piece against the stone in the precise location to be fitted. Using a standard circle compass tool, set the width to your greatest recess from the back edge of the board. Carefully scribe a line on the underside of the fill molding by moving the apex end over the stone (in line with the pencil end) perpendicular to the molding. Once the scribed line is complete, cut along the line with a jig saw using a scroll wood blade. Test the scribed fill molding and make necessary adjustments.
To ensure being able to wrap the ends with the same filler, create the front molding long on both ends. Once this process is completed, the fill pieces can be mitered, painted and fastened together in place and the crown can then be applied flush with the bottom of the filler pieces. This will increase the necessary depth and width of the crown and mantel which can then be cut to accommodate.

there ya go! smithcraft has it going on! listen to him!!!!

I think a large piece of live edge wood above the fireplace would look gorgeous!

it would srgerova!

Distressed wood!

This more natural mantel is kind of an in between.....it's not rough if you are looking for a less rustic/rough mantel....but I got the feeling you had decided on white and more formal in your look. This one is natural but sanded.