Keystones are typically placed at the top of a fireplace to provide an architectural accent. A Keystone is triangular shaped and often used with K2 Stone Thin Cobbles to border the edges of a fireplace. A custom cut keystone will add a unique finish to your fireplace. K2 Stone keystones are available in any size combination up to 24” x 24”. Keystones can be cut form Ocean Pearl Slate, Newcastle Sandstone or Crown Isle Granite.