Each bookend is cut from a natural stone and therefore will differ slightly. Approximate bookend dimensions: 4-8" Tall 6-12" Wide 4-6" Deep Agate is a very common stone that ranges in colors can range from white/grey, blue, yellow/red or even black. They are metamorphic rock that is produced through volcanoes. This volcanic activity can be seen in the layers that are common in agate. It was very abundantly used in ancient times. It is found at many archaeological sites when it was used for hardstone carving. This agate is large enough in size to be made into bookends. It is blue in color and has been polished smooth.