Set of two Oya stone design coasters. Oya stone is a pumice tuff, a stone material formed from the eruption of an underwater volcano approximately 15 to 20 million years ago. It is often used as a decorative material in architecture and contains zeolite, which has the properties of emitting negative ions and far-infrared rays. - Quantity: Set of 2 - Colors: Blue and White - Materials: Oya stone, cork backing Thank you for viewing.