These coasters have been lovingly stamped and sealed so they are waterproof. The coasters are 4" x 4" and also feature a full cork backing. They are handmade by a local Arizona artist. *Due to the handmade nature of the coaster, they are not dishwasher safe. These coasters are made of natural tumbled natural stone so there will be some slight variations, veining, pits and natural tumbled edges. The coasters are made to order and will be based on the coasters photographed.