Most local building and safety jurisdictions have rules and regulations regarding the placement of flammable materials near a fireplace. In Los Angeles, I believe that no flammable material may be placed within 12" of the fireplace opening. You may also invalidate your fire insurance by trimming your fireplace with wood. Check with your city/county and insurance carrier before making such alterations.

Thanks - there will be bluestone surrounding the actual firebox according to code - it's outside of the bluestone that I want to put this design surround rather than using a traditional mantle.