Yesterday I finished applying tile to the pizza oven. Tiles are 2"x2" tumbled travertine and think they will work well with the rest of the stone work. I applied a sealer over the tiles and will add the grout later this week. The grout is an epoxy type that should make the dome almost weatherproof. Not perfect but with one more coat of sealer, think I'll be done.
Here's a picture of the dome before the sealer was applied.
Here's a picture after the sealer, gives it a wet look and really brings out the colors in the tiles.