Blue Stone 1)swan,natural cleft 2)customized Blue Stone 3)mushroom Blue Stone 4)prompt deliverly Materials Available for all other slates, quartzite Character Low Ca , acid-resistant, non-fading Color Black, Green, Blue-black, Rusty yellow or any your need Sizes Low Ca , acid-resistant, non-fading Thickness tolerance + / -1 mm Surface Natural face, Matt surface Finished Polished, honed, flamed, ...