Cobalt Ashlar: Cobalt Ashlar combines all our cobalt bedface and splitface rubbles that stack well together to make a wonderful tapestry of shapes and textures with a mortar joint or in a linear drystack look. The yellow and white accent colours come from the vegatative and deposit bed faces of the limestone. This product was previously categorized as a rubble but most recent finished jobs show the material being laid in a more linear ashlar pattern. If you order this product in thin veneer it will look more irregular like the pictures of the fireplace.