Azgeri,
I am sure the builder can answer this for you quickly on this gorgeous project, but here is a supplier of copper tiles (porcelain) tile we have used. I really like their options for large format sizes. Good luck with your project. http://www.mosaictileco.com/apavisa_metal_copper_porcelain_tile.htm

Apavisa is distributed by Materials Inc in NY. The Apavisa flagship showroom is 472 Broome St, NY NY

These are custom 20oz copper panels with a patinated finish.

The fireplace and entry surround were paneled with individual pure copper panels contact cemented to the substrate and patinated by jimthomasbronzestudio.com with hot ferric nitrate acid. The patina was sealed with hot carnauba wax which should be re-applied annually. An alternate sealer might be Permalac.